POUNDS BUOYANCY

50 - HUMAN SUBJECTS

Mmmm SUBJECT ON CUSHION

SSS9 WAVE ACTION
40 4

to 0

NZ I~
30 4

‘oe.

—
lo 4
SAAAAAAAAAAAAAnenney] [AAAAAN AANA
° a
o 3° 60 120 180 240 300 360 420 480
(8 hrs.)

MINUTES

Ficure All. Dynamic seat-cushion evaluation conducted in February 1965 in the survival tank. Boeing 727 cushion

POUNDS BUOYANCY

50

40

30

20

10

to)

encased in a close-weave linen cover with sealed seams.

* HUMAN SUBJECTS
Mmm SUBJECT ON CUSHION
EXSSY WAVE ACTION
GR} CUSHION REMOVED FROM WATER

(TO FASTEN EXPERIMENTAL RETENTION
STRAPS)

x
\ X MACHINE EVALUATION - NO WAVES
x,

e.

= XX Nonny ge
ex —~=f=—k

w L]

o 3° 6 120 180 240

300 360 420 480 540
(8 hrs.)

MINUTES

Fiaure A12, Dynamic seat-cushion evaluation conducted in February 1965 in the survival tank. B. F. Goodrich

multifoam crew seat cushion. Blue-canvas stitched unsealed cover. Waves 2 to 2} feet in height.

12


with respect to compliance with the intent of
TSO C-72. Initially, only intermittent wave
action could be simulated. The wave generator
was constructed, and wave action could be simu-
lated more consistently throughout the 8-hour
evaluations.

Tn order to obtain some index for the magnitude
of the load applied to the cushions, body-density
measurements were made on 13 of the participat-
ing subjects (Table B1, Appendix B). The
clothing the subjects wore during the cushion
evaluations is included in the body-density re-
terminations. These determinations were made
in the Physiology Laboratory of CARI in a small
tank specifically designed for determination of
body composition. The procedure is similar to
that of Goldman and Buskirk.’ A brief description
of a determination may be found in Appendix B.

Ill. Results.

In the initial phases of this project, various
types of open-cell polyether-foam seat cushions
were pool-tested under a static load of 14 pounds
and documented by time-lapse photography.
Under these conditions, cushions successfully sup-
ported the static load for from 18 to in excess of
60 hours, therefore meeting the requirements of
the TSO as written (Figure Al). These same
types of seat cushions, when field-tested by human
subjects in light wave action, provided less than
8 minutes of adequate flotation. Buoyancy in
these dynamic tests utilizing human subjects
decreased from in excess of 32.5 to 6.0 pounds in
a 10-minute period (Figure A2). It is evident that
although these types of cushions comply with the
requirements of TSO C-72, they do not meet: the
intent of providing an adequate survivor-flotation
device. In addition, these results emphasize the
importance of a coordinated effort of both the
product engineer and human-factors investigator
in assuring an adequate and useful design.

Since the issuance of TSO C-72, seat manu-
facturers, fabricators, the airframe industry, and
airlines have developed prototype seat cushions
designed to provide individual survivor flotation.
These cushion designs generally incorporate one
or more of the following characteristics in order
to provide adequate buoyancy:

1. Multifoam construction utilizing open-cell
foam material for comfort and laminates or
wedges of a closed-cell foam material es-
sentially impermeable to water with in-
definite flotation-duration characteristics.

2. Open-cell foam-construction cushions en-
cased in a fine-weave cloth cover with
stitched and sealed seams, which, although
allowing air to pass freely during compres-
sion, are relatively impermeable to the
passage of air and water following im-
mersion.

3. A foamed-in-place cushion in which the
basic open-cell polyurethane or similar
material is mixed and allowed to react and
expand in a mold. This produces a skin
that is somewhat resistant to water pene-
tration and in prototypes has been utilized
singularly or in conjunction with a cloth
cover to produce adequate buoyancy.

4. Open-cell cushions that have been dipped
in a neoprene or similar latex compound,
producing a watertight and airtight skin.
The cushion is fitted with a valve that is
left open during normal usage but must be
closed prior to use as a flotation device.

Early prototype seat cushions failed during
dynamic testing to provide human subjects with
the 14 pounds of buoyancy specified in TSO C-72
(Figures A3 and A4). A prototype seat cushion
designed to meet TSO C-72 requirements failed
to provide adequate human flotation (Figure A5).
This cushion was pre-exposed to —40°F for 8
hours. There was no indication that this affected
the flotation characteristics of the cushion. A
CV-990 cushion that was tested but not designed
to provide survivor flotation failed in less than
8 minutes (Figure A6).

A new multifoam experimental prototype seat
cushion of wedge-type construction was evaluated
at Lake Tenkiller under field conditions for 8
hours. This same prototype cushion was subse-
quently subjected to a machine test (Figure A7).

A Boeing 727 prototype cushion consisting of
the standard 727 polyurethane core sealed in a
high-count linen cover provided very good flota-
tion for a period of 8 hours (Figure A8). A
rip or tear in this type of cover could produce a
significant loss of entrapped air and buoyancy,
depending upon the size and location of the rip
and the position in which it was subsequently
maintained by the survivor in the water.

‘A molded-foam crew seat (Massey Co.) en-
closed in a hydrojae cover with a velcra closure
and unsealed stitched seams was evaluated and
provided the required buoyancy (Figure A9).
The velcra closure separated during immersion
minus the resultant residual buoyancy appears



40-5

3B 30 a
2 1
< 1
fo) i)
5 it]
mM 20-11 9718-8 (NEW) A
\
2 \
di \
5 ot 4 'I=MOC (USED) ©
ro) Be
oa —
° se es 1 1 7

10 20 30 40 50 60
MINUTES

Ficurp A3. Dynamic seat-cushion test conducted on January 9, 1964, in the CARI 40- by 40-foot survival tank by
human subjects wearing flight suits and tennis shoes. Initial and final measurements obtained by tension
technique. Intermediate values obtained by use of lead weights, Lower bracket L indicates weight
cushion would support and upper bracket T woight that produces sinking of cushion.

40-7
re 304
g
3
5S [aa 46-8 5500-i-H8761 (NEW) al
@ 20-4
n
a
3 NE
Oo 104 WA
a. [AA7786-1-D-5160 (USED) o] A
fo}
re) ee ee ee
60 120 180 240 300 360 420 480
MINUTES (8 hrs)

Ficunn A4. Dynamic seat-cushion test conducted on January 8, 1964, in CARI survival tank. Technique same as
Figure 3. Lower horizontal portion of bracket indicates weight cushion supported. Upper T indicates
the weight that caused failure (sinking) of cushion, Both cushions tested simultaneously. Subjects
Were relieved hourly by new subjects during the test. Bar at lower edge of graph indicates time cushion
in water ani being used for flotation by subjects.

8


during compression. The expulsion of air assures
more comfortable seating characteristics than ex-
perienced with a closed-cell structure jn which
the air within the cell is compressed.

When utilized by a survivor in water, the
loading applied by the survivor, his body move-
ments, and the cyclic oscillations or bobbing in
wave action are contributing factors that pro-
duce expulsion of air from the open-cell structure
of the cushion. When immersed, the expelled
air is subject to replacement by water, producing
a loss in buoyancy in relation to the loss of air
from the open-cell material.

In Figure A4, it may be noted that measure-
ments taken by the tension technique indicate
several pounds less buoyancy than the measure-
ments utilizing a combination of lead weights.
This difference appears to be a result of the surface
tension. By monitoring the underwater spring
scale, one may observe an instantaneous drop of
several pounds in buoyant force of the cushion as
it is pulled just below the water surface and the
surface tension is broken.

Of course, if the cushion is pulled deeper, there
is a gradual but significant drop in buoyancy with
depth due to compression of air within the cellular
structure of the foam.

Although several body- and cushion-flotation
attitudes were tried, subjects tired rapidly since
both hands were required to retain the cushion.
Attempts to lie upon a buoyant cushion in the
water with the hands free were only partially
successful. Some subjects found the cushion to
be relatively stable in light wave action when they
assumed a spread-eagle supine position with the
cushion centered under the maximum curvature
of the lumbar region. When the arms and legs
were pulled in toward the body, the attitude be-
came less stable and the cushion slipped out from
under the subject and was foreibly expelled away.
This requires the survivor to swim a considerable
distance unaided to recover the cushion. Under
moderate wind conditions, the cushion may be
blown away at such a rate that it may not be
recovered.

One of the cushions was equipped with a single-
strap, snap and adjustment fitting removed from
a life preserver as shown in Figure A13.

In lieu of the above retention strap, a simple
elastic band 2 to 3 inches wide permanently
attached to both sides may be used. It is possible
that this type of retention should be donned more
rapidly than that shown in Figure Als.

Subjects wearing the cushion as shown in C and
D of Figure Al4 were maintained in a good flota-
tion position. In addition, subjects wearing the
cushion jumped into the water from 6- to 7-foot
heights without difficulty or discomfort.

A retention strap of this type design frees the
jndividual’s hands for swimming, signalling, or
assisting others. Overhand swimming is more
readily accomplished with the seat cushion re-
tained at the chest than with the airline-type life
preserver, providing the cushion is not excessively
wide.

A simple retention strap may be particularly
valuable to prevent loss of the cushion when
jumping into the water if the survivor is in-
capacitated or subjected to cold, wind, and wave
action.

Retention straps as shown in A of Figure Al4
result in the relaxed survivor being rotated
backwards and finally stabilized with the head
partially submerged and the cushion on top of
his body. A three-component strap as shown in
B of Figure A13 is better, but if utilized with
the upper edge of the cushion at chin level does
not maintain the survivor's mouth and nose suf-
ficiently above the surface in turbulent water
conditions. With the survivor’s arms resting
on the upper edge of the cushion as shown in
C of Figure A13, the survivor’s mouth and nose
are elevated higher above the water, providing
easier breathing with less effort in turbulent
water. If the survivor extends his arms as
shown in D, stabilization may be achieved with
a minimum tendency for forward or backward
rotation.

Various studies have been conducted on re-
tention systems and life-preserver design in an
attempt to develop a preserver that will ade-
quately protect the unconscious or weak and
incapacitated survivor. It is virtually impos-
sible for a conscious subject to remain inert
and flaccid, especially when his flotation atti-
tude begins to deteriorate to the point where
breathing is no longer possible. Macintosh and
Pask have used a deeply anesthetized human
subject * and also a flotation dummy 5 in order
to study retention, buoyancy, and human-body
attitudes as influenced by flotation-device de-
sign. In our studies,
would attempt to remain relaxed and motion-
less. A slow rotation of the body would begin
and the subject would attempt to persevere as

the conscious subject



therefore to be a function primarily dependent
upon the permeability of the cushion’s surface
skin as a result of the molding process. It was
subsequently determined by machine testing that
the molded cushion without a cover would main-
tain the required buoyancy for 8 hours.

AB. F. Goodrich multifoam crew seat cushion
similar in design concept to the 727 cushions in
Figures A7 and A10 provided in excess of 14
pounds of buoyancy for 8 hours (Figure A12).
The evaluations and the conditions under which
each of the preceding cushions was conducted are
summarized in Table 1.

IV. Discussion.

The typical aircraft-seat foam-cushion volume
and displacement of water is such that, if the
cushion remained totally impermeable to water,
a buoyancy of from 30 to 50 pounds would be
obtained, depending upon the size and volume
of the cushion; ie., tourist, first-class, or crew
configuration. Most frequently, aireraft-seat
foam cushions are compounded of a polyurethane
or similar open-cell structural foam. The cellular
structures are interconnected and vented to the
exterior of the foam, allowing expulsion of air

TaBiE 1. Summary of atrcraft-seat-cushion flotation evaluations.

Figure Test Date Cushion description Test location Water condition Water temp (°F) Remarks
1 Static, 14Ib static 1-63 Aerotherm 48795 jet tourist Survival tank Still 78 17 hr 29.5 min~sank
Yoad Acrotherm 45248 jet tourist 19 hr 51 min~sank
Acrotherm 43698 jet tourist ‘96 hr 40 min—test terminated
2 Dynamic, human 6-63 Aerotherm 727 jet tourist Lake Tenkiller — Choppy waves 1 89 Buoyancy measured by tension
subjects Acrotherm (two-foam) 43693 jet tourist to U4 feet technique
Aerotherm (single-foam) 45248 jet
tourist
DC-7 (foamrubber)
3 Dynamic, human 1-64 Boeing 727 9718-7 (new) Survival tank Still 84 Initfal and final measurements by
subjects Boeing 727 11-MOC (used) tension technique
Intermediate measurements by use
of lead weights
4 Dynamic, human 1-64 AA 46-B 5500-1-118/61 (new) Survival tank Still 85 Initial and final measurements by

subjects AA 7786-1-D-5160 (used) tension technique
Intermediate measurements by use

of lead weights
5 Dynamic, human 4-G4 727 new prototype 52722 mfg. to TSO Survivaltank Still 80 Buoyancy measured by tension
subjects C-72 technique. Cushion precondi-

tioned by exposure to 40°F for
8hr .

6 Dynamic, human 1-65 CV-990 single foam Survival tank Waves generated 87 Standard cushion not designated
subjects 1 to 134 feet for flotation

7 Dynamic field, —_7-64_B. F. Goodrich multifoam prototype Field test—Lake —1- to 154-foot 68
human subjects ‘Tenkiller; ma- waves;

chine test-sur- Still _
vival tank

8 Dynamic, human 2-65 Standard Boeing 727 Tourist Cushion Survival tank Waves generated 90
subjects (polyurethane core) encased in high- 14 to 2 feet

count linen (hydrojac) cloth cover.
Sealed seams.

® Dynamic, human 1-05 Massey molded crew seat enclosed in Survival tank Waves generated 90

subjects high-count (hydrojac) cloth cover. 2 to 244 feet
‘Unsealed stiched seams. Velera clo-
sure.

10 Dynamic (ma- 1-65 B. F. Goodrich experimental proto- Survival tank © Waves-generated 87 Residual buoyancy partially de-
chine test followed type multifoam tourist cushion. De- 2 t0 234 feet pendent upon open-cell foam
by buman signed to incorporate minimum closed component. Cushion machine-
subjects) foam. tested 7 days prior to human

testing. Open-cell portion of eush-
jon may not have completely
dried out following machine test.

11 Dynamic, human 2-65 Boeing 727 tourist cushion encased in Survival tank Waves generated 86
subjects a high-count (hydrojae) cover with 240 2% feet

sealedseams. This assembly enclosed
inan AA dress cover with two parallel
red retention straps.

12 Dynamic, human 2-65 B. F, Goodrich multifoam crow proto- Survival tank Waves generated 87 Buoyancy increased following brief
subjects and type cushion. Blue-canvas stitched 2 to 24 feet removal of cushion inorder toadd
machine test unsealed cover. retention system. Apparently

due to water draining from the
open-cell foam component of the
cushion.


APPENDIX A

405

. 304
o
a
4
2 48795
o | 45248
Zz
5 avo
<q a
© 104
a

° T T T T T T T T T 1
10 20 30 40 50 60 70 80 90 100
HOURS
Fraunn Al. Static seat-cushion test conducted in Mareh 1963. Cushions loaded with 14 pounds of weight and placed
in still fresh water.
40
>
(S)
Zz
a
>
fe)
2D
a
n
Qa
z
=)
fe)
a
T T T I
10 20 30 40 50 60

Fiaure A2. Dynamic seat-cushion test eondueted in June 1963 at Lake Tenkiller in open fresh water and moderate

wave action, Measurements of force of buoyancy by tension technique before and after 8 minutes of use
by human subjects in open water. Black bar at base of graph indicates duration cushions utilized by
subjects for flotation, Subjects clothed in flight suits and tennis shoes.

7



FLOTATION CHARACTERISTICS OF AIRCRAFT-
PASSENGER SEAT CUSHIONS

Ernest B. McFadden, M.S.
James M. Simpson

Approved by Released by

P. V. Srzcex, M.D.

J. Ropert Diuuz, M.D.
Feperat Arr SURGEON

Cuter, Civ AEROMEDICAL
INSTITUTE

April 1966

FEDERAL AVIATION AGENCY
Office of Aviation Medicine



40-5 © HUMAN SUBJECTS

M@@MME SUBJECT ON CUSHION
(SSS9 WAVE ACTION

3b 3048
$ Nee X MACHINE EVALUATION. ~ NO waves
x
3°
5
fra)
_ e e e e-e
g XT kee Ke aK Xe waa nm ra xe wy ey
2
S104
a L.
SSSSSSSSSSS SESS SEE EE SB BBE BBE BB EE EEE ES EEEEEEEEEESST
° a a
60 120 180 240 300 360 420 480

MINUTES (8 hrs.)

Fiovure A7. Dynamic field evaluation of a B. F. Goodrich experimental prototype multifoam 727 seat cushion conducted
in July 1964 at Lake Tenkiller in open fresh water with moderate wave action. Machine test conducted
in survival tank.

50-4
Drape kayXaxya-— - - X~ x2 ox SoS NT m= Ya a8 wy HX -x
, 40 JPses =; ow trey ekei a OX = x
8 * HUMAN SUBJECTS
< MME SUBJECT ON CUSHION
Oo 304 WAVE ACTION
5
a X MACHINE EVALUATION - NO WAVES
®
2 204
5
6
a
10 4
Q a S suas sos
°
o 3° 60 120 180 240 300 360 420 480

MINUTES (8 hrs.)

Figure A8. Dynamic seat-oushion evaluation conducted in February 1965 in survival tank, Standard Boeing 727
tourist seat-cushion polyurethane core encased in high-count linen cover with sealed seams. Waves 134
to 2 feet in height generated intermittently.

10


40 4

>

© 30 4

2

<

i } [52722 |

=)

m20 -

n

a e

2104 \

ol0 4

a °
Nene,

0 ee

10 20 30 40

MINUTES

Fiounn Ab, Dynamic seat-cushion test conducted on April 29, 1964, in CART survival tank by human subjects. Initial
and final measurements obtained by tension technique.

505

HUMAN SUBJECT

mms SUBJECT ON CUSHION
407 WAVE ACTION
304

1io4\

POUNDS BUOYANCY

30 T T T T T T T 1
° 60 120 180 240 300 360 420 480

MINUTES (8 hes)

Frours A6. Dynamic seat-cushion evaluation conducted in February 1965 in survival tank under simulated wave
conditions. CV-990 cushion not designed for flotation.

9



long as possible without resorting to corrective
action (Figure A14).

When subjects were allowed to choose their
positions, it was surprising that all male sub-
jects chose to assume a seated position as shown
by E in Figure Al4. This choice was even
more pronounced when the subjects were ex-
posed to wave conditions, as this allowed them
to float higher in the water and resulted in easier
breathing and less exertion. Although this posi-
tion appears to be quite unstable, it was a method
of choice of a majority of the subjects after they
had been in the water for a considerable time.
The strap as shown in E, Figure A14, was success-
fully tested but is not recommended due to the
final attitude a survivor would assume if balance
were lost. .

In general, the higher the head and chest
can be buoyed above the surface of the water,
the less the stress that will be imposed on the
survivor by immersion; therefore, breathing can
be accomplished easier and with more consistent
regularity in turbulent water. In addition, the
deleterious effects of profuse diuresis resulting
from stimulation of the Gauer-Henry left-atrial
volume-receptor reflex by the negative-pressure
breathing required in partial water immersion
may be reduced if a larger proportion of the chest
can be maintained above the water surface.
Diuresis begins in about 20 to 30 minutes after
immersion when the antidiuretic hormone in the
blood is depleted. Body-water loss under con-
ditions of immersion to neck level may proceed at
a rate of five to six times that of normal and
approximate 2,000 to 3,000 cc.°

V. Conclusions.

1. Static buoyancy testing of aircraft seat
cushions constructed of open-cell foam does
not simulate actual conditions of use and pro-
vides deceptive and erroneous information.

2, A simple means of attaching the cushion

to the survivor’s body should be incorporated
in cushion or upholstery design.

3. The use of a combination of open- and
closed-cell foam materials utilized in the proper
geometry for aireraft-seat-cushion construction
appears to provide a cushion that furnishes
adequate flotation with respect to quantity and
duration without significant sacrifice of seat-
cushion comfort characteristics.

4. Open-cell cushions encased in a high-count
tight-weave cloth cover with sealed seams have
maintained in excess of 14 pounds of buoyancy
for 8 hours and appear to be adequate if integrity
of the cover is maintained.

5. The result of the previous tests reaffirm
the requirement that personal, protective, and
survival equipment destined for human utiliza-
tion must be evaluated by dynamic human-
factors testing in an environment simulating as
near as practical the environment of anticipated
usage.

REFERENCES

1. Townsuenp, B. W.: Safety in over water flight, a
study of ten years’ losses of aircraft over water, Jan.
1952-Dee, 1962. _R.F.D. Company, Ltd., Godalming
Surrey, England, March 1963.

2. Federal Aviation Agency, Regulations of the Adminis-
trator, Part 514, Technical Standard Order C-72, Indi-
vidual Flotation Devices.

3. GorpMan, R. F., and Buskirk, E. R.: Body volume
measurement by underwater weighing: description of
a method, in Techniques for Measuring Body Composi-
tion, edited by Josef Brozek and Austin Henschel, Na-
tional Academy of Sciences, National Research Coun-
cil, Washington, D.C., 78-88, 1961.

4. Macinrosu, R. R., and Pasx, E. A.: The testing of
lifejackets. British Journal of Industrial Medicine,
14: 168-176, 1957.

5. Pasx, E. A, and Curistm, P. D.: Design of life-
jackets. British Medical Journal, 2: 333-335, August
1962.

6. DeForest, R. E,, and Bucxsan, E. L.: Some medi-
cal contraindications to the use of the standard life-
jacket for survival. U.S. Naval Air Development
Center, NADC-MA-6135, August 9, 1961.


this method was not entirely satisfactory. It
appeared that loss of buoyancy was not equally
distributed throughout the cushion, resulting in a
shift in the center of gravity of the cushion. Thus,
at the point where the cushion was nearly totally
immersed (and sinking imminent), the cushion and
its loading were quite unstable, having a tendency
to roll over in the water. The method of loading
the seat cushion accordingly was modified in order
to obtain a more satisfactory procedure.

This new method consisted of placing a piece
of semirigid metal hardware cloth of the same
dimensions as the cushion on its upper surface.
A brass bar was suspended. by small nylon lines
from the four corners of the hardware cloth, thus
lowering the center of gravity below the cushion.
The displacement of water due to the volume of
the submerged brass rod was determined and the
total weight of all items exclusive of the cushion
was adjusted to 14 pounds. Static tests utilizing
this technique are summarized in Figure Al.
(All Figures, Al to A14, are in Appendix A.)

The technique for dynamic testing of seat
cushions consisted of replacing the brass weight
with a calibrated spring scale, arranged in series
with the cushion and a rigidly attached bottom
slip guide. Tension was then gradually applied
to a line running to the surface. A reading of
the initial force of bouyancy was obtained by a
diver positioned near the spring scale. This
required only a few minutes on each cushion.
The cushions were then placed on the surface of
the water along with a subject clothed in a light-
weight summer flight suit and tennis shoes.
Female subjects were clothed in a swim suit under
a dress or pair of slacks. The subjects were
instructed not to squeeze the cushion unnecessarily
but just to hang on to the cushion, utilizing it for
flotation as long as they could. In field tests, a
safety buoy was provided nearby for the subject
to utilize when the cushion failed to maintain
adequate support. As soon as a subject deserted
a cushion, it was picked up and retested for
buoyancy as previously described. Field tests
were performed in open water at Lake Tenkiller
in Eastern Oklahoma. This exceedingly clear,
fresh-water lake is approximately 35 miles long
and from 2 to 4 miles wide. The water in the
vicinity of the test area is approximately 70 to
100 feet deep. All tests were filmed by motion-
picture and still photography for documentation
and further study (Figure A2). The DC-7
cushions in Figure A2 were constructed of foam

rubber and were not designed to provide flotation
but were evaluated for comparative purposes,

Another series of dynamic tests was performed
in the CARI survival tank utilizing developmental
seat cushions. Initial and final measurements
were obtained using the previously described
technique. In addition, in order to follow more
closely the time course of bouyancy loss and
check the accuracy of the spring-scale technique,
subjects were periodically removed briefly from
the cushions and tests utilizing combinations of
lead weights were also conducted (Figures A3
and A4),

In order to continue the evaluations during the
winter months and to simulate water-surface
conditions, a wave generator was designed and
constructed for use in the survival tank. This
apparatus produces waves 1% to 2% feet in height.
Because of the limited size and geometry of the
survival tank, the resultant water-surface condi-
tion might be described as similar to a choppy or
confused sea due to wave reflection from the tank
walls and the resultant reinforcement. When com-
pared to large swells such as occur in the Pacific,
the simulated conditions appear to create greater
localized turbulence. Subjects participating in
those tests in which the cushion did not fail in a
short period of time were relieved hourly with
a total of eight subjects participating during an
8-hour evaluation.

In cooperation with CARI, a study was initiated
by the Flight Standards Engineering and Manu-
facturing Field Extension to determine the reli-
ability of a cushion-evaluation technique utilizing
a machine to produce a dynamic load similar to
that of a human: subject. This apparatus was
designed to repeatedly submerge the cushion to a
predetermined depth, thereby increasing and
relaxing the external pressure on the cushion.
The machine was programmed to submerge the
sample cushion to 10 feet at a rate of about 60
cycles/hour. In practice, however, the frequency
averaged approximately 50 cycles/hour for a total
of 480 cycles (9+ hours). Subsequent tests were
conducted to a depth of 10% to 11 feet at 50
cycles/min for a total of 300 cycles (8+ hours).
Equipment breakdown and interruptions in order
to measure bouyancy account for the disparity
between the number of cycles and total elapsed
time.

Human and machine evaluations were per-
formed on a variety of prototype seat cushions
submitted by the manufacturers for evaluation


ai ai

motionless subject as induced by the retention device and relative position

Ficure Al4. Flotation attitudes of the relaxed
the direction in which the subject has a tendency to rotate.

of the cushion. Arrows indicate
18



FLOTATION CHARACTERISTICS OF AIRCRAFT PASSENGER SEAT
CUSHIONS

I. Introduction.

Due to community pressure and noise-abatement
programs, takeoff and landing flight patterns of
turbine-powered. aircraft have been increasingly
restricted to the airspace over relatively unin-
habited areas of water. Because of these trends,
if and when an aircraft accident occurs, the prob-
ability of it involving water has been propor-
tionally increased. In the event of a survivable
accident in water, provisions for flotation of
passengers and crew until rescue can be effected
become a significant problem.

The domestic air carrier is not required to
carry life preservers or rafts on aircraft operat-
ing no further than 50 miles from land. Nor is
it realistic to require the domestic air carrier to
comply with the same requirements as the over-
seas operator, whose life preservers and rafts
are designed for longer-term, open-sea survival.

In a recent report by Townshend * covering
10-year history of 102 ditchings of transport-
category aircraft, it may be noted that 30 of 36
premeditated ditchings where life rafts were
not provided, 30 occurred within 5 miles of shore.
Time required to effect rescue, available in
only a few instances, varied from 30 minutes to
6 hours.

At the request of the Flight Standards Serv-
ice of FAA, a study was initiated to determine
the flotation characteristics of items currently
aboard domestic aircraft in sufficient quantity
to .provide individual passenger and crew
flotation.

Numerous items were surveyed, and, of these
jtems, the most likely utilizable consisted of
pillows and seat cushions. Pillows were found
to be inadequate in size and volume to provide
adequate flotation, unequally distributed about
the cabin, frequently insufficient in number,
and difficult to render waterproof and at the
same time maintain the pillow’s comfort char-
acteristics.

It should be noted here that the flotation
capability of escape slides as group flotation
devices was not disregarded. A properly de-
ployed escape chute when equipped with suf-
ficient survivor hand holds has considerable
potential as a group flotation device. As an in-
dividual flotation device, however, the aircraft
seat cushion fulfilled the following criteria:

1. Potential size and volume to provide ade-
quate flotation.

2. Light weight.

3, Available in an equivalent or greater
number than passengers aboard.

4. Distributed equally with respect to pas-
senger distribution throughout the cabin.

5. Instantly available.

On July 15, 1963, the Federal Aviation Agency
issued Technical Standard Order (TSO) C-72?
covering individual flotation devices for aircraft
flying no further than 50 miles from land.
One of the provisions of this TSO stated that
an individual flotation device must provide a
minimum of 14 pounds of bouyancy for 8 hours.

II. Methods.

Initial static tests of aircraft seat cushions con-
sisted of placing the cushion in the survival tank.
Sheet lead of approximately the same flat dimen-
sions as the cushions was placed upon the upper
surface of the cushion. The weight of the sheet
lead and a small electrical recording device
attached to the lead was accurately adjusted to a
weight of 14 pounds. The test sample cushion
was surrounded by an aluminum cylinder approxi-
mately 4 feet in diameter and 3 feet in height.
This served as a wave shield and prevented
disturbances of the water surface (generated else-
where in the survival tank) being transmitted to
the test cushion.

‘An event recorder was connected to the elec-
trical indicating device. Time-lapse motion-pic-
ture cameras covered the flotation history of the
cushions. A study of these films indicated that



ACKNOWLEDGMENTS

The authors gratefully acknowledge the contributions of Dr. Vincent
Fiorica and Don Desteiguer, who interrupted a busy schedule to conduct the
body-density determinations. Acknowledgment is also made to F. F. Win-
ters, cinematographer, who under difficult circumstances filmed the tank
and field evaluations from both the surface and underwater for later study and
analysis.

Qualified requestors may obtain Aviation Medical Reports from Defense Documentation
Center. The general public may purchase from Clearinghouse for Federal Scientific and
Technical Information, U.S. Dept. of Commerce, Springfield, Va. 22151


50
| HUMAN SUBJECTS

mmm SUBJECT ON CUSHION
4044 BSS WAVE ACTION
>
Ss
z
Ss
5 307
=
ao
on
8204 bo,
2 ~~. —.—. °
3} —-_, ee
a
10-4
| AANAAANANAAAAAAAAAAAAAANAAARAARAARAARRRRERN AANANY
°
o 3° 60 120 180 240 300 360 420 480
(8 hrs.)
MINUTES
Frovrn A9. Dynamic seat-cushion evaluation conducted in January 1965 in the survival tank. Massey Company
aiidedfoam crow seat cushion enclosed in high-eount (hydrojac) cloth cover. Unsealed stitehed seams,
Velera closure, Waves 2 to 244 feet in height generated during the test.
505
* HUMAN SUBJECTS
mmm SUBJECT ON CUSHION
WAVE ACTION
40 4
>
g X MACHINE EVALUATION - NO WAVES
$
5 30 4
2D
a
wo
o 204
Zz \
3 Xyn ye aye OX aye aXe XS Ke eke OX TT TK XT Xe
o ern
to 4 a —— 0 ——  — 0 — 0 — 0 — oo —
SSS SSSSSSSSY IAAAAANAAAAAARRAAANANG
° a
o 3° 60 120 180 240 300 360 420 480
(8 hrs.)
MINUTES
Fiaure A10. Dynamic seat-cushion evaluation conducted in January 1965 in the survival tank. B. F. Goodrich experi-

mental multifoam tourist seat cushion, Waves 2 to 2)4 feet in height. Water temperature 87°F.

1



APPENDIX B

After the appropriate weight in air was ob-
tained, the subject was positioned in an under-
water chair that was suspended from a balance.
The water level was adjusted and a preliminary
underwater weight of the subject was obtained.
The subject then submersed, made a maximum
exhalation, and turned the air-control valve to
the spirometer position. The subject then made
three maximum inhalations and exhalations,
after which the air-control valve was turned
from spirometer to snorkel position. After the
final weight was obtained, the subject emersed
and a tare of the chair and breathing hose was
obtained. Nitrogen analysis of the spirometer
air was accomplished with a Med-Science Elec-
tronics Nitralizer Model 305AR. The procedure
was repeated until the subject achieved complete
exhalations as determined by a uniform recording
on the spirometer drum. The res‘dual volume
and body density were calculated as follows:

N JPR. 310
VR=V XEN, XP nar X BB pT ~ 95

VR=residual volume of lungs
V=volume of spirometer and hose
Ni=fraction of nitrogen in end-expired air
before rebreathing
No=fraction of nitrogen in end-expired air
after rebreathing
P,=barometric pressure

14

Pe=partial pressure of water vapor in spirom-
eter before rebreathing
T=temperature in spirometer before re-
breathing
47=partial pressure of water in lungs
310=absolute temperature in lungs
55=dead space in valve and mouthpeice

M
(Mi—M.)—Va

2

D=

D,=body density

M,=weight of subject in air
M,=weight of subject under water
D.=density of water at time of water
Va=residual volume of lungs

Taste Bl. Human body density, mass, and residual lung
volume of participating subjects
B . Underwater .

Subject Sez Body densiys Patt Gmbe” — Udy mass Residual es?
J.T, M 1. 0662 63, 143 3, 310 1, 285
BH M 1, 0541 74, 890 3, 060 1, 219
J.B. M 1. 0524 74, 200 2, 900 1, 222
DD. M 1, 0489 57, 880 1, 850 1, 187
DR. M 1. 0428 81, 630 3, 150 675
DB M 1. 0341 79, 380 2, 000 1, 091
AA. M 1. 0336 85, 750 2, 200 1, 092
J.G. M 1. 0266 70, 270 800 1, 388
EM. M 1, 0224 99, 550 1, 850 925
E. P. M 1. 0201 88, 290 900 1, 322
J.H. F 1. 0184 60, 940 500 966
dS. M 1, 0183 74, 860 900 894
5S. M 1. 0161 101, 620 1, 000 1, 285

“Body density and mass includes clothing worn.

U. 8, GOVERNMENT PRINTING OFFICE : 1966 0 - 224-078