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as part of a continuing program on

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aviation safety the lewis flank

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propulsion laboratory of the national

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advisory committee for aeronautics has

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been engaged in research on the start of

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fires that sometimes follow airplane

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00:00:43,670 --> 00:00:41,440
crashes the work was undertaken at the

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recommendation of the naca committee on

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operating problems and the subcommittee

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on aircraft fire prevention these groups

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are made up of leading representatives

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of civil and military aviation it was

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00:00:57,110 --> 00:00:55,280
the purpose of this research to provide

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a better understanding of the important

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factors involved in the start and spread

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00:01:04,710 --> 00:01:02,719
of crash fires as a necessary first step

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00:01:06,630 --> 00:01:04,720
leading to significant reduction in the

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00:01:08,789 --> 00:01:06,640
crash fire hazard

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the work reported in this film covers

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only the research completed on airplanes

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00:01:15,990 --> 00:01:13,600
powered with reciprocating engines

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00:01:18,710 --> 00:01:16,000
a thorough review of civil and military

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crash fire records emphasize the need

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for well-defined information on how

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crash fires start

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00:01:27,830 --> 00:01:25,280
this review showed this information can

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only be provided by full-scale crash

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study

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an naca research memorandum entitled

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00:01:40,069 --> 00:01:36,079
analysis of multi-engine transport

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airplane fire records

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the need for a full-scale crash fire

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program established the united states

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air force provided a group of service

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weary aircraft marked for decommission

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00:01:53,030 --> 00:01:50,880
with which to conduct the research a

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landing or takeoff accident was chosen

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for study because the chance for

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passenger survival of crash impact is

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highest in this type of crash which

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00:02:03,990 --> 00:02:02,079
occurs at reduced airplane speed the

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00:02:05,990 --> 00:02:04,000
airplanes were carefully instrumented to

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collect detailed information during the

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00:02:09,749 --> 00:02:06,960
crash

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72 vapor detectors located in the engine

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the cell wings and fuselage registered

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00:02:17,830 --> 00:02:14,959
the presence of combustible vapors over

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100 flame detectors similarly located

49
00:02:22,710 --> 00:02:20,080
recorded the origin and spread of fire

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throughout the aircraft structure

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00:02:26,790 --> 00:02:24,720
all the main electrical circuits were

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00:02:28,869 --> 00:02:26,800
monitored at the locations shown on this

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chart to indicate the presence of short

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circuits

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00:02:34,070 --> 00:02:31,840
instrumentation was also provided to

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indicate the time at which fuel lines

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00:02:42,229 --> 00:02:40,229
such detailed information is registered

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on this instrument panel inside a

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fireproof box carried in the airplane

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the instrument panel is photographed by

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in a crash operation the airplane is

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accelerated from rest under full power

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and is guided into a crash barrier by a

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slipper in sliding contact with a rail

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this barrier is composed of an abutment

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00:03:09,509 --> 00:03:07,360
in the path of each landing gear wheel

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00:03:11,430 --> 00:03:09,519
the abutment strip the landing gear from

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the airplane

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if propellers strike the abutment at

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full engine power to produce extensive

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damage to the engine the cell

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00:03:22,949 --> 00:03:20,400
the pair of poles on each side of the

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00:03:25,110 --> 00:03:22,959
abutment cut into the wing fuel tanks

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causing spillage of the fuel at the

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moment of crash impact the airplane is

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moving at about 90 miles an hour the

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airplane carries a thousand gallons of

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fuel in the tanks outboard of the

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nacelles the fuel is sometimes dyed red

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00:03:49,430 --> 00:03:47,430
a detailed description of the method of

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00:03:52,149 --> 00:03:49,440
conducting these crashes was published

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00:03:53,750 --> 00:03:52,159
in the naca research memorandum entitled

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00:03:56,070 --> 00:03:53,760
facilities and methods used in

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00:03:59,030 --> 00:03:56,080
full-scale airplane crash fire

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00:04:03,429 --> 00:04:01,509
to understand how crash fires begin it

86
00:04:05,509 --> 00:04:03,439
is necessary to learn where and when

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ignition sources exist and how the

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00:04:09,589 --> 00:04:07,519
combustibles move from the spillage

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00:04:11,910 --> 00:04:09,599
zones to the ignition sources while

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00:04:13,509 --> 00:04:11,920
these sources are still potent many

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00:04:15,670 --> 00:04:13,519
ignition sources are carried on the

92
00:04:17,110 --> 00:04:15,680
airplane others are generated in the

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crash area

94
00:04:21,189 --> 00:04:19,040
a large number of ignition sources are

95
00:04:23,590 --> 00:04:21,199
located in the engine nacelle which

96
00:04:25,590 --> 00:04:23,600
contains the engine and hot metal parts

97
00:04:27,590 --> 00:04:25,600
of the exhaust system

98
00:04:30,469 --> 00:04:27,600
flames appear at the engine intake in

99
00:04:32,710 --> 00:04:30,479
the familiar backfire

100
00:04:36,390 --> 00:04:32,720
likewise flames appear at the exhaust

101
00:04:40,070 --> 00:04:38,070
the electrical system of the airplane

102
00:04:42,230 --> 00:04:40,080
represents the most widely distributed

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00:04:44,790 --> 00:04:42,240
ignition source it extends from the

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00:04:47,270 --> 00:04:44,800
nacelles into the wings to power fuel

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pumps and lights into the fuselage for

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lights navigational instruments and

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airplane controls

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of the combustibles carried in an

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airplane only those in liquid form are

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likely to contact ignition sources in a

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00:05:09,749 --> 00:05:05,430
hydraulic fluid

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00:05:12,150 --> 00:05:09,759
lubricating oil and alcohol

113
00:05:14,230 --> 00:05:12,160
the crash fire threatens human survival

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00:05:16,230 --> 00:05:14,240
only when the fuel becomes involved in

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the fire because the other combustibles

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are present in small quantities however

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the other liquid combustibles may be the

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first to ignite and in turn set fire to

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the fuel

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in the conventional airplane most of the

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fuel is stored in wing tanks the tanks

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are interconnected by pipes so that fuel

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00:05:36,550 --> 00:05:34,800
from any tank can serve all the engines

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through main lines which run to the

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engine carburetor

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in a crash fuel often is spilled in

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liquid form from broken fuel lines

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likewise liquid spillage occurs from

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damaged tanks

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pre-mixed fuel vapor and air spills from

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the damaged engine induction system and

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a combustible fuel mist sometimes forms

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around the airplane the airplanes were

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crashed in ways that resulted in all

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these forms of fuel spillage

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00:06:06,870 --> 00:06:05,120
in studying how the fires are started it

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is necessary to consider the ignition

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sources along with the fuel spillage the

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following discussion will take up the

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various forms of fuel spillage and how

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the fuel moves to the ignition sources

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the characteristics of the ignition

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sources will be discussed at the same

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because the fuel in the mist form played

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such an important role in the crash

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fires experienced in this study fires

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involving fuel mist will be discussed

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00:06:37,189 --> 00:06:35,360
first when the liquid fuel spills into

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00:06:42,390 --> 00:06:37,199
the open air while the airplane is in

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in this scene shown at one-fifth normal

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speed watch how the fuel dyed red for

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visual clarity develops into mist during

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a crash as the fuel pours from the tanks

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00:06:56,870 --> 00:06:54,240
breached by the poles at the barrier the

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fuel is atomized to mist a part of which

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00:07:00,870 --> 00:06:58,960
remains suspended in the air

157
00:07:02,710 --> 00:07:00,880
the plume of the fuel mist streams

158
00:07:04,870 --> 00:07:02,720
directly rearward from the break in the

159
00:07:06,710 --> 00:07:04,880
tanks if the damage to the airplane in

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00:07:09,270 --> 00:07:06,720
the crash results in only moderate

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00:07:11,510 --> 00:07:09,280
deceleration and the airplane continues

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forward at high speed when the airplane

163
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moves at low speed with high

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deceleration the fuel surges forward out

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of the break in the tank this results in

166
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a broad fuel mist pattern in the forward

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00:07:24,309 --> 00:07:22,319
portions of the airplane under such

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conditions contact between fuel and

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ignition sources at the nacelle is

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likely

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00:07:32,070 --> 00:07:30,160
now watch in the next crash the

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00:07:34,230 --> 00:07:32,080
transition of the fuel mist development

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from the high speed low deceleration

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pattern to the low speed high

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deceleration pattern

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here comes the airplane at about 90

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miles an hour the motion is reduced to

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one-fifth normal speed the impact of the

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00:07:49,350 --> 00:07:46,880
barrier will produce momentary moderate

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00:07:51,990 --> 00:07:49,360
airplane decelerations observe that the

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fuel died red streams directly back from

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00:07:55,189 --> 00:07:53,919
the leading edge when the airplane

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00:07:57,909 --> 00:07:55,199
strikes the ground with high

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00:07:59,589 --> 00:07:57,919
deceleration the fuel mist develops well

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00:08:02,869 --> 00:07:59,599
forward of the wing leading edge and

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00:08:05,270 --> 00:08:02,879
spreads span wise as the airplane slows

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00:08:07,270 --> 00:08:05,280
in view of these effects the fuel mist

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00:08:09,350 --> 00:08:07,280
can be expected to contact an ignition

189
00:08:11,430 --> 00:08:09,360
source which lies span wise from the

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00:08:12,869 --> 00:08:11,440
point of fuel spillage as the airplane

191
00:08:14,550 --> 00:08:12,879
slows down

192
00:08:16,550 --> 00:08:14,560
in the motion pictures of the crash

193
00:08:18,469 --> 00:08:16,560
illustrating this effect look for a

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00:08:20,950 --> 00:08:18,479
continuing series of flames at the

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engine exhaust following crash impacted

196
00:08:24,790 --> 00:08:23,199
the barrier as the airplane skids along

197
00:08:27,350 --> 00:08:24,800
the ground the fuel spilling from the

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00:08:30,070 --> 00:08:27,360
wing at this location moves span wise in

199
00:08:39,509 --> 00:08:30,080
mist form until it reaches an exhaust

200
00:08:43,750 --> 00:08:41,509
now let us observe this method of fuel

201
00:08:46,070 --> 00:08:43,760
movement to the engine tailpipe the

202
00:08:52,829 --> 00:08:46,080
action here is reduced to one-fifth

203
00:08:58,470 --> 00:08:56,150
speed notice the flames at the tailpipe

204
00:09:00,870 --> 00:08:58,480
contact of the fuel mist with an exhaust

205
00:09:10,710 --> 00:09:00,880
flame occurs just as the airplane comes

206
00:09:14,630 --> 00:09:12,470
ignition of the fuel mist occurred on

207
00:09:16,630 --> 00:09:14,640
the same airplane on the hot exhaust

208
00:09:18,550 --> 00:09:16,640
collector ring of the engine on your

209
00:09:20,630 --> 00:09:18,560
left at this location

210
00:09:22,870 --> 00:09:20,640
under impact at the barrier the engine

211
00:09:25,430 --> 00:09:22,880
the cell breaks down and exposes the

212
00:09:28,070 --> 00:09:25,440
exhaust collector ring as the airplane

213
00:09:37,829 --> 00:09:28,080
slows the fuel mist moves span wise and

214
00:09:42,150 --> 00:09:39,829
here comes the same airplane watch how

215
00:09:43,829 --> 00:09:42,160
the nacelle on your left tips downward

216
00:09:46,150 --> 00:09:43,839
as the propeller hits the barrier

217
00:09:47,990 --> 00:09:46,160
exposing the exhaust collector ring the

218
00:09:49,990 --> 00:09:48,000
flame first appears at the top of the

219
00:09:56,870 --> 00:09:50,000
nacelle where the fuel mist contacts the

220
00:10:01,590 --> 00:09:58,790
in the time between initial fuel

221
00:10:03,829 --> 00:10:01,600
spillage and ignition and explosive fuel

222
00:10:05,829 --> 00:10:03,839
air mixture accumulated in the wing

223
00:10:11,030 --> 00:10:05,839
explosion of the mixture produced this

224
00:10:15,509 --> 00:10:13,509
fuels of low volatility and mist form

225
00:10:17,430 --> 00:10:15,519
ignite readily in spite of the fact they

226
00:10:20,310 --> 00:10:17,440
are safe in liquid form in the presence

227
00:10:22,630 --> 00:10:20,320
of open flames a wick saturated with

228
00:10:25,030 --> 00:10:22,640
this fuel can be ignited by the steady

229
00:10:26,710 --> 00:10:25,040
application of a flame the lighted match

230
00:10:34,630 --> 00:10:26,720
held above the surface of this low

231
00:10:39,430 --> 00:10:36,790
observe in the next crash the ignition

232
00:10:41,030 --> 00:10:39,440
of the mist of low volatility fuel by a

233
00:10:43,430 --> 00:10:41,040
tailpipe flame

234
00:10:45,750 --> 00:10:43,440
note also the backfire flame at the

235
00:10:48,150 --> 00:10:45,760
engine inlet that follows the main fuel

236
00:10:50,150 --> 00:10:48,160
ignition

237
00:10:52,630 --> 00:10:50,160
the tanks of the oncoming plane are

238
00:10:54,870 --> 00:10:52,640
filled with low volatility fuel this

239
00:10:59,509 --> 00:10:54,880
action is reduced to one-fifth normal

240
00:11:03,910 --> 00:11:01,430
here is the ignition by the tailpipe

241
00:11:20,710 --> 00:11:06,230
now watch for the backfire at the engine

242
00:11:24,870 --> 00:11:22,630
this aerial view of the crash with the

243
00:11:26,630 --> 00:11:24,880
action slowed to one third normal speed

244
00:11:28,710 --> 00:11:26,640
shows the flames traveling through the

245
00:11:37,910 --> 00:11:28,720
fuel mist at a rate comparable to that

246
00:11:41,990 --> 00:11:39,829
the flames at the engine exhaust that

247
00:11:43,910 --> 00:11:42,000
were observed igniting these mists may

248
00:11:46,790 --> 00:11:43,920
occur in a crash as long as the engine

249
00:11:48,550 --> 00:11:46,800
is rotating and drawing fuel even impact

250
00:11:50,310 --> 00:11:48,560
of the propellers with an obstacle does

251
00:11:56,550 --> 00:11:50,320
not ensure that the engine will stop

252
00:12:01,190 --> 00:11:58,949
in this crash shown at normal speed the

253
00:12:03,990 --> 00:12:01,200
damaged engines continues to operate for

254
00:12:06,389 --> 00:12:04,000
several minutes after crash impact watch

255
00:12:09,350 --> 00:12:06,399
how the propellers now in slow rotation

256
00:12:11,670 --> 00:12:09,360
accelerate this alternation of slow and

257
00:12:19,750 --> 00:12:11,680
fast rotation continues through several

258
00:12:24,150 --> 00:12:21,910
another ignition source in the engine

259
00:12:26,230 --> 00:12:24,160
cell which may ignite the fuel mist is

260
00:12:28,230 --> 00:12:26,240
provided by lubricating oil burning

261
00:12:30,310 --> 00:12:28,240
within the nacelle

262
00:12:32,470 --> 00:12:30,320
the next crash you will see shows how

263
00:12:33,350 --> 00:12:32,480
the lubricating oil can set fire to the

264
00:12:35,590 --> 00:12:33,360
fuel

265
00:12:37,670 --> 00:12:35,600
on the low wing airplane used in this

266
00:12:40,389 --> 00:12:37,680
crash the nacelle strike the ground when

267
00:12:42,150 --> 00:12:40,399
the landing gear is sheared off the oil

268
00:12:44,150 --> 00:12:42,160
cooler located at the bottom of the

269
00:12:46,310 --> 00:12:44,160
nacelle is ripped open when the cell

270
00:12:48,470 --> 00:12:46,320
strikes the ground the released oil is

271
00:12:55,269 --> 00:12:48,480
ignited on contact with the hot engine

272
00:12:59,350 --> 00:12:57,190
now we shall see how this fire setting

273
00:13:01,829 --> 00:12:59,360
process acts in a crash of a low wing

274
00:13:04,069 --> 00:13:01,839
airplane having the nacelle arrangements

275
00:13:06,389 --> 00:13:04,079
shown previously the action is reduced

276
00:13:08,710 --> 00:13:06,399
to 1 12 normal speed

277
00:13:10,629 --> 00:13:08,720
after passing through the crash barrier

278
00:13:13,030 --> 00:13:10,639
the unsupported airplane strikes the

279
00:13:15,350 --> 00:13:13,040
ground the cells foremost causing the

280
00:13:17,430 --> 00:13:15,360
oil cooler in the nacelle to break back

281
00:13:18,790 --> 00:13:17,440
and release oil onto the hot exhaust

282
00:13:21,190 --> 00:13:18,800
collector ring

283
00:13:23,670 --> 00:13:21,200
now condensed oil vapor generated on the

284
00:13:24,790 --> 00:13:23,680
exhaust system can be seen issuing from

285
00:13:27,030 --> 00:13:24,800
the nacelle

286
00:13:28,629 --> 00:13:27,040
as the airplane slows the fuel spilling

287
00:13:30,310 --> 00:13:28,639
from the wing moves out ahead of the

288
00:13:32,470 --> 00:13:30,320
leading edge and spreads toward the

289
00:13:34,870 --> 00:13:32,480
nacelle

290
00:13:36,710 --> 00:13:34,880
two seconds after crash impact ignition

291
00:13:39,190 --> 00:13:36,720
of the oil is indicated by the fire

292
00:13:41,030 --> 00:13:39,200
detectors a marked increase in the rate

293
00:13:43,590 --> 00:13:41,040
of formation of oil vapors follows

294
00:13:45,509 --> 00:13:43,600
ignition of the oil

295
00:13:47,910 --> 00:13:45,519
three seconds after crash impact the

296
00:13:49,670 --> 00:13:47,920
entire engine exhaust collector ring is

297
00:13:52,150 --> 00:13:49,680
enveloped in fire

298
00:13:54,389 --> 00:13:52,160
as the airplane comes to a stop the fuel

299
00:13:57,189 --> 00:13:54,399
mist and oil vapors form a continuous

300
00:13:59,189 --> 00:13:57,199
combustible atmosphere in a cell oil

301
00:14:01,269 --> 00:13:59,199
fire spreading through the oil mist will

302
00:14:03,350 --> 00:14:01,279
now appear outside of the nacelle and

303
00:14:05,189 --> 00:14:03,360
move rapidly to the fuel

304
00:14:07,110 --> 00:14:05,199
watch how the fire moves to the breach

305
00:14:09,269 --> 00:14:07,120
in the wing and then to the rear of the

306
00:14:11,110 --> 00:14:09,279
airplane as it follows the fuel spilled

307
00:14:17,350 --> 00:14:11,120
in the slide path of the crashed

308
00:14:21,990 --> 00:14:19,350
finally it is necessary to consider the

309
00:14:24,470 --> 00:14:22,000
time during which the mist is a hazard

310
00:14:26,710 --> 00:14:24,480
this is a rear view at one third normal

311
00:14:28,629 --> 00:14:26,720
speed which places the fuel mist between

312
00:14:30,470 --> 00:14:28,639
the airplane and the camera the

313
00:14:32,870 --> 00:14:30,480
developing fuel mist obscures the

314
00:14:35,430 --> 00:14:32,880
airplane from view but it reappears

315
00:14:37,670 --> 00:14:35,440
shortly as the large mist droplets rain

316
00:14:39,829 --> 00:14:37,680
to the ground and the small droplets are

317
00:14:42,310 --> 00:14:39,839
swept from the area by the wind as they

318
00:14:44,069 --> 00:14:42,320
evaporate these mists seldom remain

319
00:14:45,910 --> 00:14:44,079
around the crashed airplane for more

320
00:14:47,990 --> 00:14:45,920
than 15 seconds

321
00:14:50,550 --> 00:14:48,000
analysis of the photographic data shows

322
00:14:53,030 --> 00:14:50,560
that this fuel missed hazard time varies

323
00:15:00,069 --> 00:14:53,040
inversely with the wind speed around the

324
00:15:04,389 --> 00:15:01,829
to sum up it has been shown that

325
00:15:06,710 --> 00:15:04,399
airborne fuel mist can move considerable

326
00:15:08,949 --> 00:15:06,720
distance forward and span wise from the

327
00:15:11,030 --> 00:15:08,959
fuel spillage point to reach remote

328
00:15:13,110 --> 00:15:11,040
ignition sources

329
00:15:14,710 --> 00:15:13,120
when the fuel is dispersed as missed it

330
00:15:17,030 --> 00:15:14,720
ignites readily even though its

331
00:15:19,269 --> 00:15:17,040
volatility is low

332
00:15:21,509 --> 00:15:19,279
contact between the mist and an ignition

333
00:15:23,670 --> 00:15:21,519
source far from the fuel spillage zones

334
00:15:25,430 --> 00:15:23,680
is most likely to occur as the airplane

335
00:15:27,350 --> 00:15:25,440
slows down

336
00:15:29,430 --> 00:15:27,360
because of the short duration time of

337
00:15:31,350 --> 00:15:29,440
the mist the ignition source must be

338
00:15:34,310 --> 00:15:31,360
present while the airplane is in motion

339
00:15:36,069 --> 00:15:34,320
or shortly after it stops if a fire is

340
00:15:37,990 --> 00:15:36,079
to occur

341
00:15:39,910 --> 00:15:38,000
now let us see how crash fires are

342
00:15:42,389 --> 00:15:39,920
started with fuel spillage in liquid

343
00:15:44,389 --> 00:15:42,399
form fuel in liquid form appears on the

344
00:15:46,389 --> 00:15:44,399
outside of the airplane pouring to the

345
00:15:47,829 --> 00:15:46,399
ground from the broken fuel tank and

346
00:15:49,350 --> 00:15:47,839
fuel lines

347
00:15:51,749 --> 00:15:49,360
the steam that is issuing from the

348
00:15:53,749 --> 00:15:51,759
nacelle will be discussed later liquid

349
00:15:55,829 --> 00:15:53,759
fuel also collects on the airplane

350
00:15:58,230 --> 00:15:55,839
surfaces by interception of the fuel

351
00:16:00,230 --> 00:15:58,240
mist droplets while the streams of

352
00:16:02,310 --> 00:16:00,240
liquid fuel pouring to the ground are

353
00:16:04,550 --> 00:16:02,320
formed as the airplane comes to a stop

354
00:16:06,389 --> 00:16:04,560
and mist formation subsides

355
00:16:08,629 --> 00:16:06,399
spreading of the liquid fuel within the

356
00:16:10,790 --> 00:16:08,639
airplane structure begins as soon as the

357
00:16:13,350 --> 00:16:10,800
tanks are damaged regardless of the

358
00:16:15,670 --> 00:16:13,360
state of motion of the airplane

359
00:16:17,590 --> 00:16:15,680
when liquid fuel is spilled inside the

360
00:16:20,310 --> 00:16:17,600
airplane structure such as the wing

361
00:16:22,790 --> 00:16:20,320
interior combustible concentrations of

362
00:16:25,189 --> 00:16:22,800
fuel vapor accumulate readily and spread

363
00:16:27,189 --> 00:16:25,199
within the structure as an example of

364
00:16:29,990 --> 00:16:27,199
the ignition of fuel spilled within the

365
00:16:31,749 --> 00:16:30,000
wing observe the wing fire set by

366
00:16:33,110 --> 00:16:31,759
damaged landing lights on the leading

367
00:16:35,430 --> 00:16:33,120
edge of the wing

368
00:16:37,670 --> 00:16:35,440
the poles that rip open the fuel tanks

369
00:16:39,509 --> 00:16:37,680
also smash the landing lights and drive

370
00:16:41,990 --> 00:16:39,519
them into the wing where the

371
00:16:44,310 --> 00:16:42,000
incandescent filaments set fire to the

372
00:16:45,990 --> 00:16:44,320
fuel almost at once

373
00:16:48,550 --> 00:16:46,000
the next motion picture sequence

374
00:16:50,629 --> 00:16:48,560
projected at one-fifth normal speed

375
00:16:53,030 --> 00:16:50,639
shows ignition by the damaged landing

376
00:16:55,430 --> 00:16:53,040
lights the pole at the barrier drives

377
00:16:57,430 --> 00:16:55,440
the landing light into the fuel tanks

378
00:16:59,269 --> 00:16:57,440
the resulting fire spreads rapidly

379
00:17:17,590 --> 00:16:59,279
through the fuel mist to produce this

380
00:17:22,870 --> 00:17:20,470
the mass of fuel mist rises as it burns

381
00:17:24,789 --> 00:17:22,880
out the fuel evaporating from liquid

382
00:17:26,870 --> 00:17:24,799
spillage on the ground and the wetted

383
00:17:40,470 --> 00:17:26,880
surfaces of the airplane continues the

384
00:17:44,390 --> 00:17:42,470
the fuel that spills in the wing can

385
00:17:46,789 --> 00:17:44,400
also move through channels within the

386
00:17:48,870 --> 00:17:46,799
wing to ignition sources contained in

387
00:17:50,870 --> 00:17:48,880
other parts of the airplane

388
00:17:53,510 --> 00:17:50,880
one path this fuel may take is through

389
00:17:55,750 --> 00:17:53,520
the duct in the wing leading edge this

390
00:17:57,830 --> 00:17:55,760
duct carries hot air to warm the wing

391
00:17:58,789 --> 00:17:57,840
and prevent the accumulation of ice in

392
00:18:00,789 --> 00:17:58,799
flight

393
00:18:02,710 --> 00:18:00,799
the duck leads to a heat exchanger at

394
00:18:04,630 --> 00:18:02,720
the engine exhaust tailpipe which

395
00:18:06,630 --> 00:18:04,640
provides the necessary heat

396
00:18:09,110 --> 00:18:06,640
when this duct is ripped open as the

397
00:18:11,270 --> 00:18:09,120
poles tear through the wing some of the

398
00:18:13,430 --> 00:18:11,280
fuel issuing from the torn tanks is

399
00:18:16,150 --> 00:18:13,440
diverted into the duct

400
00:18:17,590 --> 00:18:16,160
this fuel flows by gravity to the hot

401
00:18:20,070 --> 00:18:17,600
heat exchanger

402
00:18:22,150 --> 00:18:20,080
upon ignition the flame flashes back

403
00:18:26,070 --> 00:18:22,160
through the hot air duct to the fuel in

404
00:18:30,070 --> 00:18:27,990
here is a crash in which these events

405
00:18:32,070 --> 00:18:30,080
occurred because the wing slopes

406
00:18:33,590 --> 00:18:32,080
gradually toward the nacelle a fuel

407
00:18:36,390 --> 00:18:33,600
flowing through the hot air duct

408
00:18:38,230 --> 00:18:36,400
requires 14 seconds to reach the cell

409
00:18:40,950 --> 00:18:38,240
since the action on film is reduced to

410
00:18:43,510 --> 00:18:40,960
one-fifth normal speed about one minute

411
00:18:45,270 --> 00:18:43,520
will pass before this ignition appears

412
00:18:53,190 --> 00:18:45,280
the steam which is issuing from the

413
00:18:57,909 --> 00:18:55,430
the fire will show first at the engine

414
00:18:59,990 --> 00:18:57,919
tailpipe heat exchanger on your right

415
00:19:07,270 --> 00:19:00,000
note the spread of the fire back to the

416
00:19:11,029 --> 00:19:09,350
in addition to the flow of liquid fuel

417
00:19:13,430 --> 00:19:11,039
through the internal channels of the

418
00:19:15,990 --> 00:19:13,440
airplane fuel and rivulets and sheets

419
00:19:18,630 --> 00:19:16,000
flows by gravity along the underside of

420
00:19:21,029 --> 00:19:18,640
inclined airplane services this will be

421
00:19:23,270 --> 00:19:21,039
called wetting conduction fuel which

422
00:19:25,270 --> 00:19:23,280
spills inside the wing can seep through

423
00:19:27,750 --> 00:19:25,280
seams in the wing's skin and cling to

424
00:19:29,430 --> 00:19:27,760
the under surface of the wing this fuel

425
00:19:31,830 --> 00:19:29,440
may then flow to other parts of the

426
00:19:34,070 --> 00:19:31,840
airplane where ignition sources exist

427
00:19:36,789 --> 00:19:34,080
the resulting fire travels back along

428
00:19:38,630 --> 00:19:36,799
the fuel path to the fuel source the

429
00:19:40,470 --> 00:19:38,640
wetting conduction of the fuel along the

430
00:19:42,710 --> 00:19:40,480
under surface of the inclined wing is

431
00:19:44,870 --> 00:19:42,720
illustrated by a simple experiment in

432
00:19:47,430 --> 00:19:44,880
which fuel issuing from an opening in a

433
00:19:50,310 --> 00:19:47,440
tube at the raised end wets and moves

434
00:19:52,310 --> 00:19:50,320
along the under surface to the low end

435
00:19:54,150 --> 00:19:52,320
the normal wing arrangement of airplanes

436
00:19:56,870 --> 00:19:54,160
may place the wingtips higher than the

437
00:19:59,190 --> 00:19:56,880
wing at the engine the cells for these

438
00:20:00,950 --> 00:19:59,200
airplanes the wetting conduction flow is

439
00:20:05,430 --> 00:20:00,960
toward the nacelle where ignition

440
00:20:09,190 --> 00:20:07,430
sometimes in a crash the wing

441
00:20:11,270 --> 00:20:09,200
inclination is even higher which

442
00:20:13,750 --> 00:20:11,280
increases the fuel movement by wetting

443
00:20:15,909 --> 00:20:13,760
conduction distribution of fuel by

444
00:20:18,310 --> 00:20:15,919
wetting conduction is shown on the

445
00:20:21,270 --> 00:20:18,320
underside of this wing of a crashed

446
00:20:23,430 --> 00:20:21,280
airplane which did not burn the fuel dye

447
00:20:25,909 --> 00:20:23,440
indicates the path of the fuel the

448
00:20:27,990 --> 00:20:25,919
continuous fuel wetted path extends from

449
00:20:32,710 --> 00:20:28,000
the break in the wing to the nacelle and

450
00:20:37,590 --> 00:20:34,870
here is how the wetting conduction flow

451
00:20:39,590 --> 00:20:37,600
looks immediately after a crash the fuel

452
00:20:42,310 --> 00:20:39,600
on the underside of the wing clings and

453
00:20:44,230 --> 00:20:42,320
flows by gravity along the wing span

454
00:20:45,830 --> 00:20:44,240
some of the fuel dripping off along the

455
00:20:48,230 --> 00:20:45,840
way

456
00:20:50,230 --> 00:20:48,240
fuel sometimes runs into the wheel well

457
00:20:53,110 --> 00:20:50,240
from broken tanks through channels in

458
00:20:54,870 --> 00:20:53,120
the wing structure

459
00:20:57,029 --> 00:20:54,880
here you see how it dripped and ran

460
00:20:59,110 --> 00:20:57,039
along various parts of the landing gear

461
00:21:08,230 --> 00:20:59,120
actuating system and along the strut

462
00:21:12,310 --> 00:21:10,549
any marked change in the surface along

463
00:21:14,390 --> 00:21:12,320
which wetting conduction of fuel is

464
00:21:16,710 --> 00:21:14,400
taking place may interrupt this fuel

465
00:21:18,710 --> 00:21:16,720
flow here we see how a sharp edged

466
00:21:20,789 --> 00:21:18,720
projection intercepts the wetting

467
00:21:26,070 --> 00:21:20,799
conduction fuel flow and prevents

468
00:21:30,070 --> 00:21:28,149
a slot in the rod provides the same

469
00:21:31,510 --> 00:21:30,080
interception of the wetting conduction

470
00:21:33,430 --> 00:21:31,520
flow

471
00:21:35,510 --> 00:21:33,440
in cases where wetting conduction or

472
00:21:37,909 --> 00:21:35,520
fuel flow through structural channels

473
00:21:40,549 --> 00:21:37,919
results in prolonged contact between an

474
00:21:43,029 --> 00:21:40,559
igniter and the fuel in liquid form the

475
00:21:47,669 --> 00:21:43,039
use of fuels of low volatility would not

476
00:21:51,830 --> 00:21:49,990
where vaporization of the fuel across an

477
00:21:54,630 --> 00:21:51,840
air gap is required for the fuel to

478
00:21:57,270 --> 00:21:54,640
reach an igniter low volatility fuel

479
00:21:59,510 --> 00:21:57,280
provides a safety advantage consider

480
00:22:01,750 --> 00:21:59,520
next fuel spilling in the open air that

481
00:22:03,510 --> 00:22:01,760
wets the ground along the slide path of

482
00:22:05,990 --> 00:22:03,520
the airplane and around the crashed

483
00:22:08,630 --> 00:22:06,000
airplane at rest the pools of liquid

484
00:22:10,710 --> 00:22:08,640
fuel close to the nacelles are not large

485
00:22:13,270 --> 00:22:10,720
since most of the spilled fuel flows

486
00:22:15,190 --> 00:22:13,280
away from the spillage point ignitable

487
00:22:17,029 --> 00:22:15,200
fuel vapor from ground spillage is

488
00:22:19,350 --> 00:22:17,039
carried in a thin layer close to the

489
00:22:21,270 --> 00:22:19,360
ground the ignition hazard distance

490
00:22:24,070 --> 00:22:21,280
which extends only a few feet from the

491
00:22:26,950 --> 00:22:24,080
spillage decreases with increasing wind

492
00:22:28,870 --> 00:22:26,960
velocity this short hazard distance is

493
00:22:31,590 --> 00:22:28,880
illustrated by the ignition of gasoline

494
00:22:33,990 --> 00:22:31,600
vapors from pans by a lighted taper

495
00:22:36,070 --> 00:22:34,000
approaching from the downwind end

496
00:22:37,990 --> 00:22:36,080
when ignition occurs the lighted taper

497
00:22:40,470 --> 00:22:38,000
lies within two inches of the surface of

498
00:22:43,029 --> 00:22:40,480
the gasoline contained in the pans the

499
00:22:45,190 --> 00:22:43,039
wind speed is 10 miles an hour movement

500
00:22:47,669 --> 00:22:45,200
of combustible concentrations of fuel

501
00:22:50,230 --> 00:22:47,679
vapors from fuels filled in the open air

502
00:22:56,070 --> 00:22:50,240
to ignition sources above the ground is

503
00:22:59,990 --> 00:22:58,070
however when the fuel is spilled into

504
00:23:02,710 --> 00:23:00,000
wind protected areas provided by the

505
00:23:05,190 --> 00:23:02,720
crashed airplane heavy ground vegetation

506
00:23:07,590 --> 00:23:05,200
or ground channels the combustible

507
00:23:09,909 --> 00:23:07,600
concentration of fuel vapors may travel

508
00:23:11,909 --> 00:23:09,919
a considerable distance the ignition

509
00:23:14,549 --> 00:23:11,919
source must appear close to the ground

510
00:23:16,710 --> 00:23:14,559
in order to contact these fuel vapors

511
00:23:19,830 --> 00:23:16,720
such ignition sources may be droplets of

512
00:23:22,149 --> 00:23:19,840
burning oil hydraulic fluid or pieces of

513
00:23:23,750 --> 00:23:22,159
hot metal broken from the engine exhaust

514
00:23:25,590 --> 00:23:23,760
disposal system

515
00:23:27,909 --> 00:23:25,600
friction sparks generated by the

516
00:23:31,029 --> 00:23:27,919
scraping of airplane metals on concrete

517
00:23:32,870 --> 00:23:31,039
runways or stony ground provide one type

518
00:23:35,110 --> 00:23:32,880
of ignition source which appears close

519
00:23:37,510 --> 00:23:35,120
to the ground these sparks may ignite

520
00:23:39,510 --> 00:23:37,520
fuel on the ground in order to study

521
00:23:41,350 --> 00:23:39,520
this type of ignition a concrete strip

522
00:23:43,750 --> 00:23:41,360
was built along the slide path of the

523
00:23:45,909 --> 00:23:43,760
crashed airplane

524
00:23:48,070 --> 00:23:45,919
selected samples of airplane metals were

525
00:23:50,310 --> 00:23:48,080
fastened to protruding ends of pneumatic

526
00:23:53,029 --> 00:23:50,320
wheel struts salvaged from airplanes

527
00:23:55,510 --> 00:23:53,039
crashed in this study upon crash these

528
00:23:57,510 --> 00:23:55,520
metal samples bear on the concrete strip

529
00:23:59,830 --> 00:23:57,520
with a contact force great enough to

530
00:24:02,070 --> 00:23:59,840
produce sparks of sufficient size and

531
00:24:04,789 --> 00:24:02,080
temperature to ignite aviation grade

532
00:24:07,190 --> 00:24:04,799
gasoline sparks from this portion of a

533
00:24:10,230 --> 00:24:07,200
steel propeller blade and this steel

534
00:24:12,149 --> 00:24:10,240
wheel strut produced fires

535
00:24:14,070 --> 00:24:12,159
a braided particles of this portion of

536
00:24:16,710 --> 00:24:14,080
an aluminum propeller blade did not

537
00:24:18,710 --> 00:24:16,720
produce ignition in order to ensure an

538
00:24:21,350 --> 00:24:18,720
ignitable mixture close to the ground

539
00:24:23,350 --> 00:24:21,360
near the sparks secondary fuel spillage

540
00:24:25,830 --> 00:24:23,360
was provided by the spray bar at the

541
00:24:30,549 --> 00:24:25,840
nose of the fuselage and these spray

542
00:24:34,470 --> 00:24:32,390
ignition will appear at this point on

543
00:24:37,669 --> 00:24:34,480
the fuselage where a portion of a steel

544
00:24:39,590 --> 00:24:37,679
propeller blade is located

545
00:24:41,830 --> 00:24:39,600
here we see the airplane sliding along

546
00:24:44,149 --> 00:24:41,840
the concrete strip after undergoing the

547
00:24:46,230 --> 00:24:44,159
usual crash damage at the barrier the

548
00:24:47,110 --> 00:24:46,240
action is slowed to one-fifth normal

549
00:24:48,630 --> 00:24:47,120
speed

550
00:24:50,470 --> 00:24:48,640
the ignition will appear at the bottom

551
00:24:52,789 --> 00:24:50,480
of the fuselage this is the first

552
00:24:54,950 --> 00:24:52,799
ignition and here is the second friction

553
00:24:57,430 --> 00:24:54,960
sparks obtained from steel and normal

554
00:24:59,350 --> 00:24:57,440
steel grinding operations seldom have

555
00:25:01,510 --> 00:24:59,360
enough size and temperature to ignite

556
00:25:03,590 --> 00:25:01,520
gasoline but these studies show that

557
00:25:06,149 --> 00:25:03,600
friction sparks of sufficient energy for

558
00:25:08,070 --> 00:25:06,159
ignition of gasoline can occur under the

559
00:25:12,230 --> 00:25:08,080
conditions of high friction loads which

560
00:25:16,549 --> 00:25:14,549
to summarize these results show that the

561
00:25:18,310 --> 00:25:16,559
ignitable vapor zones arising from

562
00:25:22,630 --> 00:25:18,320
liquid spilling in the open air are

563
00:25:24,789 --> 00:25:22,640
small except in wind protected areas

564
00:25:26,630 --> 00:25:24,799
liquid fuel spilled in the wings moves

565
00:25:28,710 --> 00:25:26,640
as liquid and vapor through the

566
00:25:30,710 --> 00:25:28,720
structural channels

567
00:25:32,630 --> 00:25:30,720
widespread distribution of a fuel in

568
00:25:34,070 --> 00:25:32,640
liquid form can occur by wetting

569
00:25:35,990 --> 00:25:34,080
conduction

570
00:25:37,750 --> 00:25:36,000
in contrast with a fuel mist which

571
00:25:40,070 --> 00:25:37,760
persists for only a few seconds in the

572
00:25:41,590 --> 00:25:40,080
crash area the fuel and liquid form on

573
00:25:43,669 --> 00:25:41,600
the ground and the wetted surfaces of

574
00:25:46,070 --> 00:25:43,679
the airplane and in the channels of the

575
00:25:47,029 --> 00:25:46,080
airplane structure are present for long

576
00:25:48,870 --> 00:25:47,039
periods

577
00:25:50,870 --> 00:25:48,880
these are the forms of fuel spillage

578
00:25:57,269 --> 00:25:50,880
that are inflamed by ignition sources

579
00:26:01,510 --> 00:25:59,510
the ignition of fuel pre-mixed with air

580
00:26:03,909 --> 00:26:01,520
in combustible proportions is another

581
00:26:05,909 --> 00:26:03,919
way in which a crash fire may begin

582
00:26:08,230 --> 00:26:05,919
such fuel air mixtures appear in the

583
00:26:10,549 --> 00:26:08,240
engine air induction system comprising

584
00:26:12,789 --> 00:26:10,559
the supercharger and engine intake

585
00:26:14,870 --> 00:26:12,799
manifold a rupture of the engine

586
00:26:16,549 --> 00:26:14,880
induction system is followed at once by

587
00:26:18,710 --> 00:26:16,559
release of the fuel air mixture

588
00:26:20,070 --> 00:26:18,720
contained under pressure by the engine

589
00:26:22,149 --> 00:26:20,080
supercharger

590
00:26:24,149 --> 00:26:22,159
ignition may occur by contact of this

591
00:26:26,870 --> 00:26:24,159
released fuel air mixture with the hot

592
00:26:29,990 --> 00:26:26,880
elements of the exhaust disposal system

593
00:26:32,470 --> 00:26:30,000
or exposed exhaust pipes by arcs and

594
00:26:40,470 --> 00:26:32,480
sparks of the electrical system or by

595
00:26:44,549 --> 00:26:42,549
because of the high air flow rates

596
00:26:46,390 --> 00:26:44,559
through the engine the cell in the early

597
00:26:48,710 --> 00:26:46,400
phases of a crash when the airplane is

598
00:26:50,870 --> 00:26:48,720
moving at high speed ignition of this

599
00:26:53,190 --> 00:26:50,880
released fuel air mixture must occur

600
00:26:55,669 --> 00:26:53,200
shortly after engine induction system

601
00:26:57,909 --> 00:26:55,679
failure otherwise the fuel air mixture

602
00:27:00,710 --> 00:26:57,919
is quickly swept from the nacelle by the

603
00:27:02,549 --> 00:27:00,720
airflow although the fire produced by

604
00:27:04,870 --> 00:27:02,559
the ignition of the engine induction

605
00:27:06,470 --> 00:27:04,880
system fuel is not serious in itself

606
00:27:09,110 --> 00:27:06,480
because of the small amount of fuel

607
00:27:11,350 --> 00:27:09,120
involved this fire can extend to other

608
00:27:14,230 --> 00:27:11,360
fuel being spilled and so set off the

609
00:27:16,070 --> 00:27:14,240
major fire in the next crash to be shown

610
00:27:18,310 --> 00:27:16,080
the engine on your right breaks out of

611
00:27:20,310 --> 00:27:18,320
its nacelle at the moment of impact the

612
00:27:22,549 --> 00:27:20,320
engine fractures along the line passing

613
00:27:24,710 --> 00:27:22,559
through the case of the supercharger the

614
00:27:27,029 --> 00:27:24,720
released fuel air mixture is ignited at

615
00:27:31,029 --> 00:27:27,039
once by exhaust flame issuing from the

616
00:27:33,029 --> 00:27:31,039
adjacent broken engine exhaust

617
00:27:35,350 --> 00:27:33,039
here the airplane approaches the crash

618
00:27:37,750 --> 00:27:35,360
barrier the action is shown at 1 12

619
00:27:40,310 --> 00:27:37,760
normal speed watch the engine in full

620
00:27:42,870 --> 00:27:40,320
view snap from its mounts ignition of

621
00:27:44,710 --> 00:27:42,880
the fuel air mixture occurs at once the

622
00:27:47,269 --> 00:27:44,720
fuel being spilled adjacent to the

623
00:27:52,630 --> 00:27:47,279
nacelle is then ignited from this flash

624
00:27:56,789 --> 00:27:55,029
another crash fire involving ignition of

625
00:27:58,789 --> 00:27:56,799
the engine induction system fuel

626
00:28:01,110 --> 00:27:58,799
occurred in the following sequence

627
00:28:03,350 --> 00:28:01,120
damage to the engine induction system on

628
00:28:05,269 --> 00:28:03,360
crash impact resulted in a fire at the

629
00:28:08,310 --> 00:28:05,279
nacelle in a manner similar to that

630
00:28:10,549 --> 00:28:08,320
shown in a previous crash

631
00:28:12,870 --> 00:28:10,559
fuel spilling from the broken main fuel

632
00:28:14,789 --> 00:28:12,880
line at the nacelle firewall was ignited

633
00:28:17,190 --> 00:28:14,799
by the flash fire of the engine

634
00:28:19,430 --> 00:28:17,200
induction system fuel the resulting

635
00:28:22,389 --> 00:28:19,440
flames streamed rearward over the

636
00:28:24,070 --> 00:28:22,399
nacelle and wing

637
00:28:25,830 --> 00:28:24,080
afterwards the fuel spilling from the

638
00:28:28,310 --> 00:28:25,840
wings through the ruptures cut by the

639
00:28:30,470 --> 00:28:28,320
poles at the crash barrier fanned out

640
00:28:32,310 --> 00:28:30,480
into the wake of the wing contact

641
00:28:34,389 --> 00:28:32,320
between the flames and the fuel took

642
00:28:40,789 --> 00:28:34,399
place to the rear of the trailing edge

643
00:28:44,630 --> 00:28:43,110
the flames moved forward to the wing

644
00:28:46,870 --> 00:28:44,640
through the trailing fuel as the

645
00:28:51,510 --> 00:28:46,880
airplane speed fell below the flame

646
00:28:55,990 --> 00:28:53,590
now watch this fire setting mechanism in

647
00:28:58,310 --> 00:28:56,000
the next movie sequence at normal speed

648
00:29:03,590 --> 00:28:58,320
watch the nacelle and note the forward

649
00:29:07,190 --> 00:29:05,510
the research up to this point resulted

650
00:29:09,350 --> 00:29:07,200
in an understanding of the ignition

651
00:29:12,070 --> 00:29:09,360
sources involved in a series of crash

652
00:29:14,470 --> 00:29:12,080
fires and also how the fuel in the mist

653
00:29:16,870 --> 00:29:14,480
liquid and vapor forms moved from the

654
00:29:19,110 --> 00:29:16,880
spillage point to the ignition sources

655
00:29:21,350 --> 00:29:19,120
however these ignition sources revealed

656
00:29:23,830 --> 00:29:21,360
so far usually produced fires within a

657
00:29:25,750 --> 00:29:23,840
few seconds after crash impact

658
00:29:28,070 --> 00:29:25,760
because it was felt these early fires

659
00:29:30,710 --> 00:29:28,080
might mask other ways in which fire can

660
00:29:38,149 --> 00:29:30,720
occur the known ignition sources were

661
00:29:42,070 --> 00:29:40,549
the parts of the inerting system used in

662
00:29:44,630 --> 00:29:42,080
this investigation are shown

663
00:29:46,870 --> 00:29:44,640
diagrammatically on this chart

664
00:29:49,430 --> 00:29:46,880
here are the main parts of a typical

665
00:29:51,350 --> 00:29:49,440
engine nacelle to prevent the appearance

666
00:29:53,909 --> 00:29:51,360
of flames at the engine inlet and

667
00:29:56,630 --> 00:29:53,919
exhaust outlet fuel system shutoff

668
00:29:59,029 --> 00:29:56,640
valves are installed at the engine

669
00:30:01,029 --> 00:29:59,039
and the firewall to stop the fuel flow

670
00:30:03,029 --> 00:30:01,039
following crash impact

671
00:30:04,870 --> 00:30:03,039
one valve stops the fuel flow to the

672
00:30:07,830 --> 00:30:04,880
engine the other prevents the fuel

673
00:30:09,990 --> 00:30:07,840
spillage into the nacelle several pounds

674
00:30:12,470 --> 00:30:10,000
of suitable fire extinguishing agent

675
00:30:15,350 --> 00:30:12,480
discharged uniformly in the engine inlet

676
00:30:17,350 --> 00:30:15,360
air to inert the contents of the engine

677
00:30:22,070 --> 00:30:17,360
during the period of time required for

678
00:30:27,029 --> 00:30:24,310
electrical system switch shuts down the

679
00:30:28,710 --> 00:30:27,039
airplane battery and generator circuits

680
00:30:30,710 --> 00:30:28,720
the ignition system continues to

681
00:30:32,389 --> 00:30:30,720
function so that fuel passing into the

682
00:30:34,950 --> 00:30:32,399
engine will be burned in the normal

683
00:30:37,110 --> 00:30:34,960
manner in case the fuel shut off valves

684
00:30:40,070 --> 00:30:37,120
and the fire extinguishing agent system

685
00:30:42,389 --> 00:30:40,080
at the engine inlet are slow to function

686
00:30:45,110 --> 00:30:42,399
normal engine exhaust is less likely to

687
00:30:47,269 --> 00:30:45,120
start a fire than tail pipe flame which

688
00:30:49,909 --> 00:30:47,279
forms that when the fuel charge passes

689
00:30:52,070 --> 00:30:49,919
through the engine cylinder unburned and

690
00:30:53,190 --> 00:30:52,080
is later ignited in the hot exhaust

691
00:30:55,269 --> 00:30:53,200
system

692
00:30:57,510 --> 00:30:55,279
in order to prevent ignition on the hot

693
00:30:59,990 --> 00:30:57,520
metal of the exhaust system a water

694
00:31:01,750 --> 00:31:00,000
spray is used to cool all of the exposed

695
00:31:04,230 --> 00:31:01,760
metal which is hot enough to ignite the

696
00:31:06,389 --> 00:31:04,240
combustible in a few seconds needed to

697
00:31:08,789 --> 00:31:06,399
cool the metal to safe temperatures and

698
00:31:10,470 --> 00:31:08,799
inert atmosphere of steam generated by

699
00:31:13,190 --> 00:31:10,480
the water evaporating from the metal

700
00:31:15,669 --> 00:31:13,200
itself shrouds this potential ignition

701
00:31:17,590 --> 00:31:15,679
source to render it impotent the portion

702
00:31:19,909 --> 00:31:17,600
of the water spray system which services

703
00:31:22,230 --> 00:31:19,919
the exhaust collector ring is this

704
00:31:24,310 --> 00:31:22,240
three-quarter inch diameter tubing bent

705
00:31:26,710 --> 00:31:24,320
to conform approximately to the shape of

706
00:31:28,789 --> 00:31:26,720
the collector ring the exhaust system

707
00:31:30,630 --> 00:31:28,799
receives water over its entire surface

708
00:31:32,630 --> 00:31:30,640
from its spray nozzle

709
00:31:34,789 --> 00:31:32,640
the effectiveness of the water spray in

710
00:31:36,549 --> 00:31:34,799
preventing ignition on the hot exhaust

711
00:31:39,029 --> 00:31:36,559
is demonstrated by the rapidity with

712
00:31:40,710 --> 00:31:39,039
which a continuously fed oil fire

713
00:31:43,029 --> 00:31:40,720
burning from the exhaust system is

714
00:31:44,870 --> 00:31:43,039
extinguished by the water spray

715
00:31:47,190 --> 00:31:44,880
notice how the application of the water

716
00:31:59,190 --> 00:31:47,200
spray extinguishes the fire almost at

717
00:32:03,190 --> 00:32:01,110
this crash is typical of the results

718
00:32:05,110 --> 00:32:03,200
obtained with five aircraft equipped

719
00:32:06,950 --> 00:32:05,120
with the experimental inerting system

720
00:32:09,029 --> 00:32:06,960
just described which is arranged to be

721
00:32:11,430 --> 00:32:09,039
actuated as soon as possible after a

722
00:32:13,509 --> 00:32:11,440
crash impacted the barrier

723
00:32:15,350 --> 00:32:13,519
the only visible sign of the functioning

724
00:32:17,990 --> 00:32:15,360
of the inerting system is the steam

725
00:32:19,669 --> 00:32:18,000
evaporating from the hot exhaust system

726
00:32:22,149 --> 00:32:19,679
this is the steam which was visible in

727
00:32:24,149 --> 00:32:22,159
some of the preceding pictures the fuel

728
00:32:26,070 --> 00:32:24,159
here has been dyed red

729
00:32:28,070 --> 00:32:26,080
see the dust being raised by the

730
00:32:30,789 --> 00:32:28,080
airplane fuselage skidding along the

731
00:32:32,549 --> 00:32:30,799
ground this dust plays an important part

732
00:32:33,590 --> 00:32:32,559
in starting fires to be described

733
00:32:35,830 --> 00:32:33,600
shortly

734
00:32:37,830 --> 00:32:35,840
this experimental inerting system used

735
00:32:39,990 --> 00:32:37,840
in this crash was devised solely for

736
00:32:42,070 --> 00:32:40,000
studies of this kind and does not

737
00:32:44,070 --> 00:32:42,080
incorporate the considerations of weight

738
00:32:45,830 --> 00:32:44,080
and bulk which would be involved in

739
00:32:47,190 --> 00:32:45,840
inerting equipment for operating

740
00:32:49,190 --> 00:32:47,200
aircraft

741
00:32:51,029 --> 00:32:49,200
in this phase of the research in which

742
00:32:52,789 --> 00:32:51,039
aircraft carrying the experimental

743
00:32:56,070 --> 00:32:52,799
inerting system were subjected to

744
00:32:58,470 --> 00:32:56,080
moderate damage upon crash impact no new

745
00:33:00,870 --> 00:32:58,480
ignition sources were revealed

746
00:33:02,630 --> 00:33:00,880
after five crashes in which no fires

747
00:33:04,630 --> 00:33:02,640
were obtained and no new ignition

748
00:33:06,789 --> 00:33:04,640
sources were observed the crash

749
00:33:08,870 --> 00:33:06,799
circumstances were modified in an effort

750
00:33:12,070 --> 00:33:08,880
to learn other ways in which fires may

751
00:33:14,149 --> 00:33:12,080
occur in order to learn whether ignition

752
00:33:15,990 --> 00:33:14,159
sources may be created by the tearing

753
00:33:17,750 --> 00:33:16,000
and twisting of the airplane structure

754
00:33:19,590 --> 00:33:17,760
in a severe crash

755
00:33:21,350 --> 00:33:19,600
the forward portion of the fuselage

756
00:33:25,029 --> 00:33:21,360
structure was crushed along this

757
00:33:26,870 --> 00:33:25,039
inclined line in one crash as before the

758
00:33:28,870 --> 00:33:26,880
nacelles carried the experimental

759
00:33:30,950 --> 00:33:28,880
inerting system in the pictures which

760
00:33:32,870 --> 00:33:30,960
follow note the complete collapse of

761
00:33:34,870 --> 00:33:32,880
this fuselage force structure bringing

762
00:33:36,630 --> 00:33:34,880
the wings to ground level and the

763
00:33:42,870 --> 00:33:36,640
resulting wetting of this structure by

764
00:33:46,870 --> 00:33:44,710
while no fire occurred around the

765
00:33:49,110 --> 00:33:46,880
crushed structure ignition of the fuel

766
00:33:51,350 --> 00:33:49,120
did occur in the fuel wetted wake of the

767
00:33:53,590 --> 00:33:51,360
airplane the ignition source was an

768
00:33:55,990 --> 00:33:53,600
electric spark discharging to the ground

769
00:33:58,070 --> 00:33:56,000
from the landing gear strut which broke

770
00:33:59,750 --> 00:33:58,080
off in the crash and tumbled in the wake

771
00:34:01,830 --> 00:33:59,760
of the airplane

772
00:34:04,149 --> 00:34:01,840
here the airplane approaches the crash

773
00:34:06,389 --> 00:34:04,159
barrier upon impact with the ground the

774
00:34:09,109 --> 00:34:06,399
forward structure collapses the action

775
00:34:11,109 --> 00:34:09,119
here is slowed to one-fifth normal speed

776
00:34:12,950 --> 00:34:11,119
now watch the wheel strut tumbling in

777
00:34:15,190 --> 00:34:12,960
the wake of the airplane and observe the

778
00:34:17,349 --> 00:34:15,200
ignition which occurs when the metal end

779
00:34:19,190 --> 00:34:17,359
of the strut approaches the ground the

780
00:34:21,510 --> 00:34:19,200
fire spreads through the fuel in the

781
00:34:23,030 --> 00:34:21,520
airplane wake there is no evidence of

782
00:34:25,349 --> 00:34:23,040
other ignition resulting from the

783
00:34:28,629 --> 00:34:25,359
destruction of the fuselage structure or

784
00:34:30,149 --> 00:34:28,639
the inerted engine the cells the igniter

785
00:34:32,069 --> 00:34:30,159
in this instance proved to be an

786
00:34:34,389 --> 00:34:32,079
electric spark discharging from the

787
00:34:36,310 --> 00:34:34,399
landing gear strut to the ground the

788
00:34:38,550 --> 00:34:36,320
necessary electrical potential on the

789
00:34:40,470 --> 00:34:38,560
strut was generated in its passage

790
00:34:47,510 --> 00:34:40,480
through the dust and fuel mist in the

791
00:34:52,230 --> 00:34:49,669
ground studies were conducted by blowing

792
00:34:54,069 --> 00:34:52,240
dust and fuel over a landing gear strut

793
00:34:55,990 --> 00:34:54,079
and measuring the electrical potential

794
00:34:58,470 --> 00:34:56,000
built up on the surface of the landing

795
00:35:01,030 --> 00:34:58,480
gear here is the landing gear strut

796
00:35:03,109 --> 00:35:01,040
electrically insulated from its supports

797
00:35:05,190 --> 00:35:03,119
when dust is introduced into the air

798
00:35:06,870 --> 00:35:05,200
blowing over the strut at speeds equal

799
00:35:09,510 --> 00:35:06,880
to that of the strut moving through the

800
00:35:11,430 --> 00:35:09,520
air in the crash potentials in excess of

801
00:35:13,829 --> 00:35:11,440
twenty thousand volts are generated on

802
00:35:16,230 --> 00:35:13,839
the strut almost at once

803
00:35:18,710 --> 00:35:16,240
this voltage applied across a spark gap

804
00:35:20,790 --> 00:35:18,720
located in this small pan containing a

805
00:35:23,430 --> 00:35:20,800
pool of gasoline produces ignition of

806
00:35:27,030 --> 00:35:23,440
the gasoline

807
00:35:29,030 --> 00:35:27,040
here is the flaming gasoline

808
00:35:31,349 --> 00:35:29,040
in the last crash of this series the

809
00:35:33,270 --> 00:35:31,359
effect of an airplane ground loop on the

810
00:35:35,829 --> 00:35:33,280
distribution of the spill fuel was

811
00:35:38,550 --> 00:35:35,839
studied watch how the airplane ground

812
00:35:40,470 --> 00:35:38,560
loops as one landing gear is torn away

813
00:35:43,270 --> 00:35:40,480
the ground loop places the airplane and

814
00:35:45,190 --> 00:35:43,280
the fuel spray the fuselage wing and the

815
00:35:47,750 --> 00:35:45,200
cell on the right side of the airplane

816
00:35:50,069 --> 00:35:47,760
are wetted heavily with fuel because the

817
00:35:52,630 --> 00:35:50,079
inerting system carried on this airplane

818
00:35:55,990 --> 00:35:52,640
functioned properly and no new ignition

819
00:35:57,910 --> 00:35:56,000
sources appeared no fires occurred

820
00:36:00,310 --> 00:35:57,920
and now here's a summary of the crash

821
00:36:02,790 --> 00:36:00,320
fire research from two lewis flight

822
00:36:04,710 --> 00:36:02,800
propulsion laboratory scientists irving

823
00:36:07,109 --> 00:36:04,720
pinkel associate chief of the physics

824
00:36:11,109 --> 00:36:07,119
division and merit preston chief of the

825
00:36:13,430 --> 00:36:11,119
flight research branch mr pinkle

826
00:36:15,349 --> 00:36:13,440
the results of this work indicate that

827
00:36:17,589 --> 00:36:15,359
significant reduction in crash fire

828
00:36:18,630 --> 00:36:17,599
hazard can be realized by design

829
00:36:22,390 --> 00:36:18,640
measures

830
00:36:24,950 --> 00:36:22,400
that increase the span wise and forward

831
00:36:28,150 --> 00:36:24,960
distance and the elevation of the

832
00:36:30,069 --> 00:36:28,160
engines with respect to the fuel storage

833
00:36:32,470 --> 00:36:30,079
this trend in airplane component

834
00:36:35,349 --> 00:36:32,480
arrangement decreases the likelihood of

835
00:36:37,589 --> 00:36:35,359
contact between the fuel mist

836
00:36:38,829 --> 00:36:37,599
and the many ignition sources located at

837
00:36:42,630 --> 00:36:38,839
the engine in the

838
00:36:45,750 --> 00:36:42,640
cell fuel stored in wingtip tanks or in

839
00:36:47,990 --> 00:36:45,760
pods suspended below the wing represent

840
00:36:50,230 --> 00:36:48,000
current design trends

841
00:36:51,670 --> 00:36:50,240
which decrease the likelihood of contact

842
00:36:54,790 --> 00:36:51,680
between the fuel

843
00:36:56,390 --> 00:36:54,800
and the ignition sources devices or

844
00:36:58,870 --> 00:36:56,400
design features

845
00:37:01,349 --> 00:36:58,880
which act to intercept spilled fuel

846
00:37:03,910 --> 00:37:01,359
flowing within the airplane structure

847
00:37:05,589 --> 00:37:03,920
are also valuable

848
00:37:07,589 --> 00:37:05,599
provisions for the drainage of this

849
00:37:10,069 --> 00:37:07,599
intercepted fuel

850
00:37:12,310 --> 00:37:10,079
into the open air at spillage points

851
00:37:14,150 --> 00:37:12,320
away from the engine the cells

852
00:37:16,150 --> 00:37:14,160
would enhance the effectiveness of these

853
00:37:18,470 --> 00:37:16,160
arrangements

854
00:37:20,230 --> 00:37:18,480
location of landing lights away from

855
00:37:22,310 --> 00:37:20,240
cordwise positions

856
00:37:24,310 --> 00:37:22,320
in front of the fuel storage is

857
00:37:26,390 --> 00:37:24,320
indicated as well

858
00:37:28,870 --> 00:37:26,400
because these studies show how readily

859
00:37:31,109 --> 00:37:28,880
combustibles spilled in the cell are

860
00:37:33,750 --> 00:37:31,119
ignited it is desirable that the

861
00:37:36,230 --> 00:37:33,760
components of the fuel lubricating and

862
00:37:38,550 --> 00:37:36,240
hydraulic systems should be located high

863
00:37:40,950 --> 00:37:38,560
in the cell where crash damage to these

864
00:37:43,349 --> 00:37:40,960
compounds is least likely

865
00:37:45,430 --> 00:37:43,359
tubing containing combustibles should be

866
00:37:47,670 --> 00:37:45,440
designed to accommodate the cell

867
00:37:49,510 --> 00:37:47,680
distortions accompanying propeller and

868
00:37:51,910 --> 00:37:49,520
the cell impact

869
00:37:54,150 --> 00:37:51,920
preliminary data suggests the value of

870
00:37:55,829 --> 00:37:54,160
employing special paints which reduce

871
00:37:58,150 --> 00:37:55,839
the tendency toward the formation of

872
00:38:00,069 --> 00:37:58,160
electrostatic sparks on parts of the

873
00:38:01,030 --> 00:38:00,079
airplane likely to be detached in the

874
00:38:03,670 --> 00:38:01,040
crash

875
00:38:06,150 --> 00:38:03,680
and trail in the dust and fuel in the

876
00:38:08,150 --> 00:38:06,160
wake of the crashed airplane

877
00:38:09,109 --> 00:38:08,160
in an approach to an indicated price

878
00:38:11,030 --> 00:38:09,119
landing

879
00:38:12,950 --> 00:38:11,040
the pilot should de-energize all of the

880
00:38:14,150 --> 00:38:12,960
electrical system not required for the

881
00:38:15,910 --> 00:38:14,160
landing

882
00:38:17,990 --> 00:38:15,920
engine operation that provides the

883
00:38:20,150 --> 00:38:18,000
coolest exhaust disposal system should

884
00:38:22,230 --> 00:38:20,160
be practiced consistent with other

885
00:38:24,310 --> 00:38:22,240
safety considerations

886
00:38:26,550 --> 00:38:24,320
just before touchdown the fuel flow to

887
00:38:29,349 --> 00:38:26,560
the engine should be cut off to allow

888
00:38:31,190 --> 00:38:29,359
the engine to be purged with clean air

889
00:38:33,109 --> 00:38:31,200
in view of the effectiveness of the

890
00:38:35,349 --> 00:38:33,119
experimental ignition source alerting

891
00:38:37,510 --> 00:38:35,359
system in preventing crash fires

892
00:38:39,510 --> 00:38:37,520
experienced in this research

893
00:38:42,630 --> 00:38:39,520
further study of this system for special

894
00:38:44,790 --> 00:38:42,640
airplane application is desirable

895
00:38:47,589 --> 00:38:44,800
material covered in this motion picture

896
00:38:50,630 --> 00:38:47,599
has been published in an naca research