(tied
anes

2 Il

The
toy
wien

us
=
cc
=
Lia alll -

from }

ns, oo”

a. A 1943 Boeing Stearman
A-75 crashed at a steep
angle with sufficient
force ta drive the top
wing forward but did not

flip over,

“This aircraft was equipped with
“both shoulder harness and seat
belt, “but the pilot was wearing
only. the lap. belt (loosely) and a
-eloth helmet, . The neck impact
with. the top of the instrument
panel fractured the pilot's larnyx
and. drove the neck vertebra back
ta such an extent ag to completely -
sever the spinal cord. He should .
have survived without injury if he-
had been wearing properly his
shoulder harness and seat, belt,

19



as b Both shoulder traps
_. broken, lap belt held,

Pte 2 Vi ew of an’ aire raft involved

| 13



by Upward bending of inertia reel
oo and lap belt attachment puints
che - to lower fuselage tubing behind
2. the cockpit,

Hae

eere Inertia reel torn loose by |
ss crash forces,

Bee,
By. ie



b,

Shoulder straps and lap
belt held in this minor —
accident but it should be
noted that the shoulder.
straps are becoming)
frayed (see arrow) and .
would be sure to fail in
an accident of greater >.
crash severity, 06).

Minor accident of a 1968 Pipe
presented to show the use o



a. Side view of an aircraft involved in a
severe crash, Severity of crash is 1
by failure of motor and its mounts, collapse
of the hopper and partial collapse of cabin.

c, Left seat belt cable broken from

6, As shoulder harne ae became siack and .

¥

crash forces,

are

4

the left seat belt cable broke, pilot was

thrown into right forward corner of ©

cockpit {note heavy radio). —

ndicated |

20

b. Upward bending of ine rtia recl
attachment on lower fusclage
tubing to rear of cockpit allow-

ed slack in shoulder harness &

forward movement of the pilot.

d, Right seat belt cable badly
frayed but did not break.

~The pilot of this 1965 Piper Pawnee
{(PA.25-235) received severe but noo-

fatal injuries after failure of his re-
straint equipment (see captions above).
His most severe injuries, including

extensive fractures ofhis right hip,

iliac crest, wristand elbow, resulted

‘from bedy contact with the heavy raclio

(Fig, e}. Inaddition he suffered frac.
tures of both legs below the knees fram
floor structure failure. Head injurics
consisting ofa small lace ration onthe
right side of his face and slight concus-
sion were major since his head was
thrown over the right side of the cock -
pit. . .

Accident investigated by D. Rawlan,



am

2
Br
te

es ee ge
CL ae

ia Te
Fc

type ‘alurmin nwt roll,

_botharms and bath legs- -all fram fo rward body
tion after restraint failure. |

Ace ideat. investigated by J Blethy

Pilot also. suffered rac

22



a ¢ Moderately Severe ¢ crash.

Since this aircraft is not equipped with sho
and the pilot was wearing

severe head: injuri gina crash of this severity. The f

his seat belt, one would pane

that the pilot escap' a without inju y must Soe by.
nit his : large padded



ended

t and
Ninor

npacl

b, Close-up showing damage to roll
bar structure--strong cnough in
this instance ta prevent collapse

& Phato-

graph of
the pilot-—
no
injuries,

on the pilot,

a. View of aire raft
after being turned
back right side up,

A 1963 Piper Pawnee (PA-25-235) was involved in a
iinor crash and rolled over into an inverted position.
Pilot was wearing both lap belt and shoulder harness
and there was no failure of this restraint equipment.
Use of proper restraint and the integrity of the roll
bar cage prevented any injuries in this accident,

Accident investigated by J. Blethraw and E, Langston,

CASE 5


SHI AMM eter doasucd a

bh, Protective aluminum rell
undamaned nn

on soft earth,
and a crash hi init, that broke the

He was. avearing shoulder phages:



a th Pawnee the Agwagon ig equipped
with a ee sgmmioylindet of aluminum at the:

iy

sna Agwagon crashed in tall
ad 40. eet, ‘before: coming ta rest (minor crash
_dece levation fa ces). The pilot was wearing his
2 » lap belt & and a crash. heb net and

¢, Ewen in this very minor
accident the shoulder
strap stitching: has
started to. fail.



een enone ne ET Ne ee ee ae ee a tee

wes HAE cet we
ve PS OE

GROUP IV

Case 12: This Stearman crashed at & steep
angle. The top wing struts failed (Case 12-0)
‘na forward direction due to forward momentum.
Although a shoulder harness was available, the
pilot was only wearing his lap belt (loosely ad-
justed) and a cloth helmet. The front of the
instrument panel was padded with foam rubber,
but since the pilot was wearing a loosely-adjusted
belt, his head was thrown above the padding and
his neck impacted the top (unpadded) portion
of the panel (see arrow, Case 12~c} with sufficient
force to fracture the Jarnyx, displace cervical
vertebra, and completely severe the spinal cord.
Since the cockpit did not collapse and the air-
craft did not become inverted, the pilot probably
would have survived this accident with minor
injuries had he been wearing his shoulder harness

and a tight lap belt.

Case 13: This 1965 Piper Pawnee was involved
in a severe accident which resulted in structural
failure of the engine mounts, hopper, and part
of the cockpit. The pilot was wearing his
shoulder harness, the lap belt and a crash helmet.
He sustained injuries of a survivable nature be-
cause of a combination of failures of his restraint
system. The left cable to the lap belt broke (Case
13-c) and the attachment point of the inertia
reel and right lap belt cable (lower fuselage
tubing) buckled upward (as in Case 8) allowing
considerable slack in the restraint system (Case
13~b). As a result of these restraint system
failures, the pilot was thrown into the right front
portion of the cockpit. Forceful contact of his
pelvis against the heavy radio (Case 13-e) re-
sulted in a fracture of the upper right femur and
right iliac crest. He also suffered fractures of
both legs below the knees and fractures of the
right wrist and right elbow. Stronger lap belt
eables and relocation of the attachment point of
the inertia reel are indicated.

18

Case 14: This 1960 Pawnee crashed unde
similar circumstances as those described in (
18. Both halves of the lap belt and both shoul
straps broke (Case 14~-b) allowing the pilot to
thrown forward, burying his knees in the fi
glass hopper and his face in the aluminum ser
cylinder at the top of the instrument panel (C
14-c). The yield characteristics of the fiberg!,
and the light aluminum roll were such as to pre. |
duce only minor injuries. The condition of the!
Jap belt and shoulder harness indicated the}
webbing was old and probably under-strengih, |
again emphasizing the need for periodic insper. |
tion and replacement of the restraint system, |

Case 15: This 1968 Aerocommander Calloir a
was involved in a crash similar to the two f
Pawnees described in the two previous cases and, |
as in Case 14, the age of the webbing caused th |
lap belt to break in two places (Case 15-1). As 1
the lap belt broke, the single shoulder strap (tied |
to the belt with nylon rope) offered no resistance |
to the forward motion of the pilot; his face im 4
pacted the instrument panel (Case 15-c). Th
need for light aluminum semicylinders at the top |
of the instrument panel is clearly evident when
the minor head injuries of the pilot in Case 14 ay
compared to the fatal crushing injuries of th
face and cranium of the pilot in this crash (Cag
15-f), The forward motion of the pilot as}
caused fractures of both arms and both legs. Us
of newer webbing and the installation of an mr
pact attenuation device at the top of the instr |

ment panel would probably have permitted ths |
pilot to survive with minor injuries.

“|
a -
y .

4
Case 16: This 1964 Piper Pawnee crashed in
verted at a steep angle. Forces were of suc}
magnitude as to cause almost complete destruc 1 ‘.
tion of the aircraft and the accident should le {
classed as nonsurvivable. The pilot died fiom}
multiple fractures and a ruptured heart. :

iz;
u



GROUP II

Case 3: This 1963 Piper Pawnee was in a
minor crash landing and was flipped over onto its
back. The pilot (Case 5-c) was wearing his
shoulder harness, a lap belt, and a crash helmet
and was uninjured. A significant hazard noted
in this accident relates to incipient failure of the
roll bar structure in this minor flip-over; slightly
more force would probably have resulted in total
failure and crushing of the pilot.

Case 6: A 1964 model Piper Pawnee descended
through small trees and crashed in a river. The

pilot, wearing his shoulder harness, lap belt and
crash helmet, was subjected to relatively minor
deceleration forces. However, the roll bar struc.
ture failed in the welded corners during impact
with the trees forcing a sharp tube-end back into
the cockpit (Case 6~-b and c); the pilot sustained

a fatal puncture wound just above his left eye
(Case 6-d).



IV. Conclusions.

The modern fleet of aerial applicator aircraft
that have incorporated the crashworthy design.
features of the AG-1 are, indeed, a rugged breed
of aircraft. Some pilots are undoubtedly sur-
viving crashes equalling 80 to 40 G’s or more
with minor or no injuries. On the other hand,
fatalities and serious injuries are occurring in
crashes of much lower deceleration. The analysis
of crash injuries presented in this study has
shown that most injuries and deaths in aerial
applicator crashes are not attributable to failure
of cockpit structure itself, but rather to factors
associated with pilot restraint and/or seat
failures, failure of the roll-over structure, and
lack of head impact attenuators at the top of the
instrument panel.

Based upon our observation, it is concluded
that increased survival and reduced injuries
would accrue if the following modifications were
made:

1. Equip all aircraft with inertia reels;

9. Attach all inertia reels to structure that js
least likely to deform or fail during a survivable |

crash ;

8. Strengthen lap belt and shoulder harness
cables ;

4, Design the restraint system so that the pilot
must wear the shoulder harness when he wears
the lap belt;

5. Replace lap belts and shoulder harnesses

every five years, or sooner if signs of fraying or |

deterioration become evident;

6. Use a more positive seat tie-down with
double lock pins;

7. Incorporate light aluminum semicylinders or
similar structures at the top of the instrument
panels of all aerial applicator aircraft to help
prevent head injuries.

Moreover, a stronger roll-over structure should
be designed.

REFERENCES

1. National Research Council, Committee on Aviation
Medicine, Report #230, 17 Nov. 1948.

National Research Council, Committee on Aviation
Medicine, Report #440, 9 July 1945.

3. DeHaven, Hugh: Crash Research From the Point of

View of Cabin Design. Aeronautical lingineering Re-
view, Vol. 5 #6. Jan. 1946.

re)

4, DeHaven, Hugh: Development of OGrash-Survival
Design in Personal, Executive and Agricultural Air
craft. Crash Injury Research, Cornell University
Medical College, N.Y., N.¥., May 1958.

5. Hasbrook, A. Howard: What a Spray Plane Should
Have. Aviation Week, 18 Feb. 1950, pp. 25-81.

23282

| AVIATIO!
| BIBLIOG

3

OC kth at's}
karen N

| £. Jean

a Farforming ©

FAA Cis
PrP, O, ]
dklahor

| i Sponsoring
| Office
Federa
800 In
Washin

| 3. Supplemen
This 1
’ ‘4 Abstract

An an
prese
funct
of Sp
cardi
anima
ine li

| OW, Key ¥

Tra
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1 Ferm DC


TECHNICAL REPORT STANDARD TITLE PAGE

Se

; 1. Report No. ~ | 2, Government Accession No. 3. Recipient's Catalog No.
| | FAA-AM~72-15
4, Title and Subtitle 7 5. Report Date ~
CRASH SURVIVAL ANALYSIS OF 16 AGRICULTURAL April 1972
AIRCRAFT ACCIDENTS &, Performing Organization Code
, ) #, Author(s) Oo 8. Performing Organization Report No.
J. J. Swearingen, D.Av.T.; T. F. Wallace;
_ | J. G. Blethrow; and D. E, Rowlan
} ?, Performing Organization Name and Address. 10. Work Unit No.
FAA Civil Aeromedical Institute
P. 0. Box 25082 11. Contract or Grant No.
Oklahoma City, Oklahoma 73125
13. Type of Report and Period Covered
2 — 12. Sponsoring Agency Name and Address a 7
| | Office of Aviation Medicine
| | Federal Aviation Administration |
q 800 Independence Avenue, S.W. 14. Sponsoring Ageney Code SS—~—CS—S~S
Washington, D.C, 20591
15. Supplementary Notes 7 OO
7 Research leading to preparation of this report was performed under Projects
| | AM-A-72-PRS-37 and AM-A-71-PRS-37,
7
' { 16. Abstract ; |

This study presents pertinent findings from on-the-scene investigations to

| | evaluate the crashworthiness of the present fleet of agricultural applicator

# | aircraft. A detailed presentation of 16 crashes illustrates the fact that most

E | of these specialized aircraft structures are well designed to protect the pilot,

a even in severe crashes. Most injuries and deaths of aerial applicator pilots

| are not attributable to failure of the cockpit structure itself, but rather to

1 Factors associated with (1) pilot restraint equipment, (2) seat failures,

q (3) failure of the roll-over structure, and (4) a lack of head impact attenuators
4 at the top of the instrument panel,
L

7 17. Key Words 18, Distribution Statement |
7 Crash injury, structural parts, Availability is unlimited, Document may
i aviation accidents, aircraft design, be released to the National Technical

: aircraft seats, restraint installation, Information Service, Springfield,

| agricultural aircraft, head impact, Virginia 22151, for sale to the public.
Be a = ene _ ee ee
4 19. Security Classif. (of this report) 20. Security Classif. (of this page) 21. No. of Pages | 22, Price

: Unclassified Unclassified 24 $3.00

Form DOT F 1700.7 (a-69)



GROUP III

Case 7: Although most lap belts and shoulder
arness straps are not marked with a manufac-
uring date, it is believed the pilot of this 1964
Piper Pawnee was wearing restraint equipment
probably manufactured during World War IL.
If this is true, the webbing was 25-30 years old.
Sinee the 25-G hopper (and cockpit) were un-
damaged, it may be assumed the cockpit decelera-
tion was less than 25 G’s—yet both shoulder
straps failed about six inches ahead of the cable
attachment point (‘The lap belt held).

Unfortunately, cotton webbing materials de-
terlorate with age, and with exposure to the
elements and insecticides, and become frayed with
long usage. Since the cockpits of most agricul-
tural aircraft are designed to withstand 40-G
crashes, it is imperative that the pilot’s restraint
equipment be changed periodically if he is to
survive such decelerations without serious injury.
In this instance, the pilot was jackknifed over
his lap belt and his face was buried in the light
auminum semicylinder (Case 7~c) designed to
yield and distribute crash force over a large area
of the head. Because of the excellent yield
characteristics of this structure, the pilot received
only a slight concussion and a small laceration of

his chin from contact with the altimeter reset
knob (Case 7-d),

Case 8: The crash force and structural damage
involved in the 1969 Pawnee case shown here
appear to be similar to those related to the 1964
model described in Case 7. However, this air-
craft, (manufactured five years later) may have
been equipped with a newer shoulder harness.
It is also noteworthy that while the lower ends
of the shoulder straps are sewn to the lap belt,
they are also wrapped around the belt and sewn
al the way throngh (Case 8-c), as compared to
Cases 2, 3, and 9, in which the shoulder straps
are stitched to only one face of the belt. Sur-
prisingly, although the pilot was wearing both
shoulder straps and lap belt and there was no
failure of the webbing or cables, a head impact
depression was found in the aluminum semi-
cylinder at the top of the instrument panel (Case
§-d). In this aircraft the inertia reel and lap
belt cables are attached to a cross tube in the
lower fuselage, back of the seat. In this crash,
the lower tube was buckled up (Case 8~b) allow-
ing 10 inches of slack in the shoulder harness and

11

right half of the lap belt. This permitted the
pilot to move forward, striking the top of his
head on the broken windshield. The aluminum
semicylinder undoubtedly prevented serious facial
injuries.

Case 9: This 1970 Cessna Agwagon was in-
volved in a moderately severe crash and the pilot,
wearing his shoulder harness, lap belt and crash
helmet, escaped with only bruises. As mentioned
before, the shoulder harness is attached to solid
structure in the roll bar framework in this air-
craft and has no inertia reel (Case 9-c). As in
Case 2, because of the lack of an inertia reel, the
pilot usually wears his shoulder straps loosely
adjusted to provide good vision and maneuver-
ability in the cockpit. In this accident, the slack
in the shoulder straps allowed the pilot’s head to
strike the aluminum semicylinder (Case 9-b).
The use of an inertia reel in this aircraft would
probably have prevented this head strike despite
failure of the seat-lock pin which allowed the
seat to slide forward and detach itself from the
tracks,

In a 40-G cockpit, the pilot should be given
the protection of a 40-G seat tie-down. Rather
than a lightweight single lock-pin, heavy duty
lock-pins in both tracks seem to be indicated.

Case 10: In this accident involving a 1969
Aerocommander Callair, the pilot, who was wear-
ing a crash helmet and had adjusted his shoulder
harness and lap belt snugly, sustained only

bruises from the shoulder straps. This appears
to be an excellent installation of body restraint
equipment, including a metal-to-metal attach-
ment of the shoulder straps to the lap belt (Case
10-e). The shoulder straps pass over the pilot’s
shoulders, through an opening behind the pilot,
and down to a strong tubular frame structure
behind the seat, However, caution should be
observed in the maintenance of this restraint
system because of webbing contact with the rough
edges of the opening behind the seat. The less
than two-year-old shoulder straps in this air-
craft already showed signs of fraying (Case
10-d). Such fraying seriously reduces the
webbing strength. Also, the restraint system
should include an inertia reel. The snugly ad-
justed belt. and harness prevented the pilot’s head
from striking the instrument panel. Without any



a
sleet

—

b, Close-up showing failure of roll bar
structure,

a. Side view of aircraft after bein |
pulled out of the water, |

d. Puncture wound (fatal)
just below edge of hel-
met inflicted as. broken
roli bar was forced

" | down and to the rear

c. Broken weld joint of vertical | | | into the cockpit.
har formed sharp cutting edge
{see arrow).

Minor crash of a 1964 Piper Pawnee (PA-25.
#235). The pilot, wearing shoulder harness, a
lap belt and crash helmet, flew through some .

trees and crashed ina river, Impact force 7 _

with the tree limbs caused roll bar failure . .
resulting in the fatal puncture wound (the only
facial injury) shown in figure d above,

Accident investigated by J, Blethrow.

10



nye of
My von :

Close- ups showing csckpit area with

crash in. trees,

: oe ) “Airevait was equipped with shoulder bon ee |
harnesses but the pilot was not. be TE he
wearing. them, a are a . ae

d.

os his Callair probably. experienced s some rather high G
forées as it broke off som trees G to 8 inches in dia-
The pilot stated that he avoided head injury by
feet up on the instrument panel when he saw

meter, .
bracing hi
he wa S going ta crash,

Accident inventigated by T. | Wallace.

TOR eta! 2nd) mem epee cee

ow Med en nas



bh. Farce ofimpact was sufficient ta
break bath shoulder straps and
the 3~in, lap beltintwo places,

a, Side view of an aircraft in-
voived ina very severe steep
angie impact with hard ground,

d, Photograph of pilot four
days after the crash.

ce, Dent in light semicylinder of alumi- |
num fram head impact of pilot, |

Considering the severity of the crash jmpact of this 1960

Piper Pawnee (PA-25), it is worth note that the pilot

escaped with relatively minor injuries; namely, a fracture
wo of the right frontal sinus, moderate concussion, fracture
ce, of left ankle, and minor cots.

Accident investipated by J, Simpson and J, Biethrow,

pn CASE 14

21



ti} sence between this aircraft and the one discussed

jer, |
dy | 3c). Again, attention is called to the aluminum
ntl | gmicylinder at the top of the instrument panel
ts) (Case 8-b) and to the shoulder straps stitched to

tone |
tH Tis no sign of failure of the stitching in this case.

ach. |
| trees of moderate diameter.

| was equipped with shoulder harness and lap belt,

belt

m Case 2 18 the presence of an inertia reel (Case

me surface of the lap belt (Case 8-d). There

Case 4: A 1969 Callair crashed and hung in
While the aircraft

the pilot was using only the lap belt; he wore no

crash helmet. He said he escaped injury by
putting his feet up on the instrument panel and
bracing himself when he saw he was going to

crash. This is, indeed, a poor practice and
agricultural pilots should be educated to utilize
upper torso restraint. In a crash of greater
severity, this pilot would probably have sustained
fatal head injuries from impact with the rigidly
designed instrument panel (See Case 15).



et

3

pilot resulted from the upward. failu:

. Side view of aircraft showing con

siderable damage to right. wing
motor mount, and lower fuselage.
tubing to the. rear of. the. cockpi

Photograph showing that restraint
“equipment remained. intact

The pilot of this 1969 Piper Pawne
(PA-25-235) received laceration
the top of his head from the. broken

. : ¢
num semicylinder (designed for he:

impact protection), and a slight kne
laceration, All forward motion of the

of the inertia reel and right seat bell
attachment point, © -



otk

4, A moderately severe c rash of at

sha *

Pea Averocommander. Callair A-
and the uninjured pilot.

b “Rigid. instrument panel without -
head impact protection,

od 1. Shoulder atrap webbing |
is becaming frayed and -
“should be replaced,

This young pilot survived with only shoulder
“strap. bruises a moderately severe crash since
hé was wearing strong, reliable restraint: .
equipment and a crash helmet, |

“Accident investigated by T, Wallace, |

Metal-to- metalattachment
of shoulder straps to lap helt.
forms amore reliable re-
straint system than sewing 9
shoulder straps toone sur.
face of the belt, oo


Aewagon, Aerocommander Quail and Callair,

and the Grumman Ag-Cat all meorporate many
of the crash safety design features of the AG-1.

It is the purpose of this report both to evaluate
the erashworthy features incorporated in these
aircraft on the basis of analysis of on-the-scene
crash investigations, and to point out areas where
crash safety design of these specialized aircrait
might be improved by only minor structural
changes.

This study presents pertinent findings from
nine Piper Pawnee crashes (of which three were
of minor severity, one was moderately severe,
four severe, and one very severe), two Cessna
Aewagons ‘(one minor and one moderately
severe), and two Aerocommander Callairs (one
moderately severe and one severe). Although the
World War IT Boeing Stearman was not designed
for aerial application and does not have the
specifically designed crashworthy features of the
new agricultural aircraft, there still are a large
number of Stearmans in use in the aerial ap-
plication industry and for that reason two
erashes (one moderately severe and one severe)
are included in this report.

TI. Method.

The 16 crashes presented are divided into four
groups on a basis of accident severity and in-
volvement of roll-over structure.

Group I: Minor—engine mounts, hopper and
cockpit intact.

Group II: Same as Group I—Minor, but roll-
over structure involved.

Group III: Moderately Severe—engine mounts
destroyed but hopper and cockpit intact.

Group TV :.Severe—engine mounts, hopper and
cockpit severely damaged.

III. Results and Discussion.

GROUP I

Case 1: A pilot wearing a shoulder harness, a
lap belt, and a crash helmet crashed in a 1968
Piper Pawnee on level ground; the aircraft’s
landing gear was destroyed. While this crash
is described as minor, it must be kept in mind
that the term is a relative one, applying only to
the discussion of these well-designed agricultural
aireratt, The same crash forces in some general
aviation aircraft might have produced serious

injuries. The upper torso restraint, lap belt, and |

crash helmet protected the pilot from injury

buckle,

Case 2: As in Case 1, this 1968 Cessna {
Agwagon was involved in a minor crash, sliding |
135 feet in a field of tall cotton, before coming to |
a stop. The pilot was also wearing shoulder {
straps, 1 lap belt, and a crash helmet and escaped
without injury. Three observations are worthy |

of note in this accident. First, note (Case 2-c}

the strong, high attachment point of the shoulder
Note also that |

harness to the roll bar structure.
the harness is attached to solid structure without

an inertia reel, thereby limiting the motions of

the pilot’s upper torso. In many cases, pilots

wear this harness loosely adjusted to provide
them with better reach for control and outside |
vision. Second, the ends of the shoulder straps -
are stitched to only one face of the lap belt |
(Case 2-d) instead of either being wrapped
around the belt and then sewn, or attached to the —
buckle by use of a metal-to-metal unit as in the
Pawnee shown in Case 1. It is believed that this —
type of shoulder strap attachment (sewn on one |
side only) constitutes a weak link in this other- |

wise rugged agricultural aircraft. In fact, it can

be seen in Case 2-e that the stitching began to |
fail even in this minor accident. Third, the light ©
semicylinder of aluminum at the top of the in- }
strument panel (Case 2-b) is designed to reduce ]
head impact forces and to distribute force over |
large areas of the face and head. This protective

device has proved to be most effective in the re-
duction of head injuries.

Case 3: An identical aircraft to that described ©

in Case 2 (a 1968 Cessna Agwagon) was involved

in a minor crash, sliding 175 feet in soft earth. |

The landing gear was torn off and, as the right
wing gouged into the soft earth, the pilot was

thrown to the right, his head breaking the -
He was wearing his j
shoulder harness, a lap belt and a crash helmet |
and escaped without injury. One noticeable dit |

window on that side.

by ’ :

However, the frayed shoulder straps indicated by |
an arrow in Case 1-b are indicative of a potential _
hazard. This aircraft was less than three years —
old and, while the frayed straps were strong |
enough to hold in this accident, they probably |.
would have failed in a more severe crash. In |
addition, please note the metal-to-metal attach. |
ment of the shoulder harness to the lap belt }

$$ $—amagges


CRASH SURVIVAL ANALYSIS OF 16 AGRICULTURAL
AIRCRAFT ACCIDENTS

{ 1, Introduction.

- Over 20 years ago, through the joint efforts of
1 the Departments of the Army, Navy and Air
} Force; the Civil Aeronautics Administration; the
| Department of Public Health and Preventive
‘Medicine, Cornell University Medical College;
and the A &M College of Texas, an aircraft
known as the CAA-Texas A & M agricultural air-
eraft was designed and built. Designated the
AG-1, this aircraft (Figure 1) embodied radi-
eally new crashworthy features advocated in the

Ficure 1. Photograph of the original CAA—Texas
A & M's (AG—1) agriculture airplane in flight.

field of crash safety as early as 1948 by pioneers.

like DeHaven and Hasbrook+?%4* and was the
forerunner of most of the aerial applicator air-
craft in use today. Perhaps the most important
crashworthy feature of this aircraft was the
design that placed the pilot far back in the air-
craft in a heavily reinforced 40~G cockpit. The
AG-1 provided 18 feet of crushable structure
ahead of the pilot for absorption of energy dur-
Mg erash decelerations. In a head-on crash,

According to Professor Fred Weick, the designer,
the initial impact would be partially absorbed

by the 15-G engine mount; any remaining crash
energy would then be transferred to the firewall
structure just ahead of the hopper. After failure
of the hopper-fuselage structure—at 25 G’s—the
cockpit then could collapse only if the remaining
deceleration were in excess of 40 G’s. In addition,
the aircraft was equipped with a 40-G seat, mih-
tary lap belt, and integral two-strap harness with
an inertia reel. ._In brief, it was anticipated that
the pilot of an aircraft with these design features
would survive—without serious injury—a head-
on collision at speeds up to 75 miles/hour.

Although only one AG-1 was built (it crashed
without injuring the pilot—Figure 2), it served
as a prototype for the present fleet of aerial ap-
plicator aircraft. The Piper Pawnee, Cessna

SS elie aN GUE Sens (uae NEM

Fiaure 2. Scenes at the crash site on


energy attenuating device (padding or aluminium
roll) for head impact protection, any head strike
would probably have proved disastrous (See

Case 15).

Case 11: The Boeing-Stearman was designed
prior to America’s entry into World War II and
was used as a military primary trainer. As such,
it was designed as a rugged aircraft, able to with-
stand moderately severe crashes without being
totally destroyed, Many of these aircraft, pur-
chased as “surplus” planes, were converted and
used for agricultural aircraft purposes.

12

Since a large number of these aircraft are still
being used in aerial application work, two acci-
dents are included in this report.

This Stearman flipped over after initial im-
pact. Despite the fact that the aircraft was not
equipped with shoulder harness, the pilot escaped —
without injury. However, the crash force was |
sufficient to throw the pilot forward over his |
lap belt and his head struck the roll of padding |
at the top of the instrument panel (Case i1-c), |
Also, the pilot was protected from being crushed |
under the inverted aircraft by the top wing which |
acted as a roll-over structure. |



View of a moderately
severe crash ofa Pa7a
Cessna Apwapron (PE SSB)}

b. ‘Pilot: was “wearing his” Be
. shoulder: straps loosely, ae
allowing bis head ‘to strike, _—

‘the aluminum roll (see _

ZZ  g, Asin previous
- --- gases, shoulder
: i Ooh straps stitched =
: Pihot ofthis : aire ra ft ree ety fod anya 3 to belt surface, .
i |. fatalinjuries could haveoteur red but did not fail.
i ment panels not equi ipped Ww ith t He

OE RINT IL AEE ESTEPONA

. CASE 9

15