DOT/FAA/AM-17/1

Office of Aerospace Medicine

Washington, DC 20591

Comparison of AC and 

Original Formulation 

ConforTM Foam

Performance in Civil Aircraft 

Vertical Impact Tests

Amanda M. Taylor

Richard L. DeWeese

David M. Moorcroft

Civil Aerospace Medical Institute 

Federal Aviation Administration 

Oklahoma City, OK 73125

January 2017

Final Report
NOTICE

This document is disseminated under the sponsorship of 

the U.S. Department of Transportation in the interest of 

information exchange. The United States Government 

assumes no liability for the contents thereof.

___________

This publication and all Office of Aerospace Medicine 

technical reports are available in full-text from the 

Civil Aerospace Medical Institute’s publications website: 

http://www.faa.gov/go/oamtechreports
i

Technical Report Documentation Page

1. Report No. 2. Government Accession No. 3. Recipient's Catalog No.

DOT/FAA/AM-17/1

4. Title and Subtitle 5. Report Date

Comparison of AC and Original Formulation ConforTM Foam

Performance in Civil Aircraft Vertical Impact Tests

January 2017

6. Performing Organization Code

7. Author(s) 8. Performing Organization Report No.

Taylor A, DeWeese R, Moorcroft D

9. Performing Organization Name and Address 10. Work Unit No. (TRAIS)

FAA Civil Aerospace Medical Institute

P.O. Box 25082

Oklahoma City, OK 73125

11. Contract or Grant No.

12. Sponsoring Agency name and Address 13. Type of Report and Period Covered

Office of Aerospace Medicine

Federal Aviation Administration

800 Independence Ave., S.W.

Washington, DC 20591 14. Sponsoring Agency Code

15. Supplemental Notes

16. Abstract

Rate sensitive foams are often used in aircraft seat designs; recently, the formulation of one of the more 

common types of foam, ConforTM, was changed. The previous Standard version came in four stiffness levels, 

which all met aircraft flammability requirements. The new version still has four stiffness levels; however, 

each type will consist of two formulations, one designated ConforTM M and one designated ConforTM AC.

The Federal Aviation Administration’s Civil Aerospace Medical Institute (CAMI) conducted testing to 

determine whether occupant injury risk during vertical impacts would be affected by substitution of the AC 

material in place of the original material in seat bottom cushions incorporated in dynamically qualified seats.

A combination of original ConforTM foams obtained from stock at CAMI and the reformulated aerospace 

ConforTM supplied by Skandia, Inc., were dynamically tested on a rigid seat. The anthropomorphic test 

dummy used was the 50th percentile male FAA Hybrid III. In addition to lumbar loads, occupant kinematics, 

as well as seat pan loads and floor loads were gathered. 

ConforTM foam comes in four different degrees of stiffness and is color-coded to avoid confusion. The two 

mid-stiffness foams, CF-42 (pink) and CF-45 (blue), were selected for this evaluation because they are the 

most commonly used types in aviation. The ConforTM original and AC formulation foams were evaluated at 

two test severities and two thicknesses. Due to limited material availability, only one test configuration was 

repeated. The 4-inch thick, AC formulation pink foam was tested three times at 19 G, producing a lumbar 

load range of 25 lb.

The 4-inch buildup blue ConforTM foam produced a difference in the normalized lumbar load of 14 lb more 

for the AC version at 14 G and 44 lb less for the AC at 19 G. The 4-inch buildup pink ConforTM foam 

produced a difference in the normalized lumbar load of approximately 53 lb more for the AC version at 14 G 

and 190 lb more for the AC at 19 G. The largest difference in peak lumbar load produced by the AC version 

was 11% greater than the original version. If some level of production variability is assumed, then these 

values suggest that there may not be a significant difference between the impact performance of the original 

and AC formulation for aircraft bottom seat cushion applications.

17. Key Words 18. Distribution Statement

ConforTM, Cushion comparison, FAA Hybrid III 

Vertical, Lumbar load

Document is available to the public through 

the Internet:

http://www.faa.gov/go/oamtechreports/

19. Security Classif. (of this report) 20. Security Classif. (of this page) 21. No. of Pages 22. Price

Unclassified Unclassified 19

Form DOT F 1700.7 (8-72) Reproduction of completed page authorized
ii

ACKNOWLEDGMENTS

The work would be unable to be completed without the full support of the technical staff at CAMI, Jeff 

Ashmore, Jim Biegler (Contractor for Cherokee CRC), David DeSelms, and Ronnie Minnick.

We also thank Gary Palmer of Skandia, Inc., for providing the AC formulation ConforTM materials.
iii

Contents

COMPARISON OF AC AND ORIGINAL FORMULATION CONFORTM FOAM

PERFORMANCE IN CIVIL AIRCRAFT VERTICAL IMPACT TESTS 

BACKGROUND ............................................................................................................................................................ 1

METHODS ...................................................................................................................................................................... 1

Test Device ................................................................................................................................................................... 1

ATD Seating ................................................................................................................................................................. 2

Test Set Up ................................................................................................................................................................... 3

Instrumentation ........................................................................................................................................................... 4

Restraint ........................................................................................................................................................................ 6

Cushion ......................................................................................................................................................................... 6

Data Processing ........................................................................................................................................................... 7

Test Matrix ................................................................................................................................................................... 7

RESULTS ......................................................................................................................................................................... 7

Blue ConforTM.............................................................................................................................................................. 9

Pink ConforTM .......................................................................................................................................................... 11

Test Repeatability ..................................................................................................................................................... 13

DISCUSSION ............................................................................................................................................................... 14

LIMITATIONS ............................................................................................................................................................ 15

CONCLUSION ............................................................................................................................................................ 15

REFERENCES ............................................................................................................................................................ 16
1

COMPARISON OF AC AND ORIGINAL FORMULATION CONFORTM FOAM 

PERFORMANCE IN CIVIL AIRCRAFT VERTICAL IMPACT TESTS

BACKGROUND

In a vertical impact, the seat bottom cushion plays a vital role in controlling the load transferred to the 

occupant’s spine. The Federal Aviation Administration (FAA) has standards and regulations in place to protect occupants in the event of a crash. Dynamic testing is required by these standards in order to substantiate the safety of seating systems. One of the two dynamic tests required is a primarily vertical impact of 30° 

off vertical. In this test, the principal measurement is the compressive load in the lumbar spinal column, 

which has a regulatory limit of 1500 lb [1].

One commonly used type of foam, well suited to this application due to its rate sensitive qualities, is 

ConforTM. This type of foam has been used in aircraft seat designs for many years; however, a recent product bulletin announced that the original line of Standard ConforTM is being replaced with two updated versions [2]. This change was necessary to comply with restrictions on the use of certain fire retardant chemicals used in the original foam’s formulation. The previous Standard version came in four stiffness levels, 

which all met aircraft flammability requirements. The AC version still has four stiffness levels; however, 

each type will consist of two formulations, one designated ConforTM M and one designated ConforTM AC.

These still have the loading rate sensitivity and slow recovery attributes as the previous foams, however, only the ConforTM AC is designed to meet the flammability requirements for use in aviation seating systems.

The effect on lumbar load of substituting this AC foam in seating systems qualified with the original foam is 

unknown. This could affect seats being currently produced as well as spare cushions for seats in service.

This unknown prompted testing to compare the original and AC formulations in order to quantify the potential impact on both new seats entering service and the continued safety of seats currently in the fleet. 

METHODS

To compare the dynamic performance of the AC and original ConforTM formulations, a series of 18 sled 

tests were carried out on the acceleration servo-sled at the Civil Aerospace Medical Institute (CAMI). 

Test Device

The Anthropomorphic Test Device (ATD) used to assess injury risk was a 50th percentile male-sized 

FAA Hybrid III. This ATD differs from the standard Hybrid III used in automotive testing because it has 

been modified to better emulate the more upright posture of an occupant in an airliner seat and provide 

kinematic and vertical load response equivalent to the Hybrid II [3]. The modification consists of several 

Hybrid II parts substituted into the structure including the lumbar spine, abdominal insert, chest jacket, and 

upper leg bone (Figure 1). The Hybrid II or an equivalent, such as the FAA Hybrid III, is currently required 

for certification tests of aviation seats. The FAA Hybrid III was selected for this project because its pelvis is 

manufactured to tighter dimensional tolerances than the Hybrid II, having a vertical height tolerance of 

±0.07 inch versus ±0.2 inch for the Hybrid II. The same ATD was used for all tests in this project to further maximize repeatability. 
2

Figure 1. FAA Hybrid III; Orange Outlined Parts are Hybrid II

ATD Seating

To minimize the effect of seat frame flexibility on the test results, a rigid seat pitched up at a 60° angle 

was used to compare the different foams. The nominal upright ATD seated position (1-G position) was determined with respect to the seat cushion for each test article. To facilitate making this measurement, a surrogate wooden seat was fabricated with geometry, pan, and back angles identical to the rigid test seat (Figure 

2).

For this measurement, the ATD was seated in accordance with a procedure developed at CAMI that results in a very consistent fore/aft position and initial pelvis angle [4]. This procedure involves suspending 

the ATD above the seat cushion just enough to insert a flat hand (approximately 1 inch) between the bottom of the pelvis and the cushion. A rigid bar is then inserted under the thighs just aft of the knees and used 

to elevate them slightly so as not to interfere with the ATD self-aligning. A force gage is used to press on 

the sternum of the ATD with approximately 20 lb of force while the ATD is lowered into full contact with 

the seating surface. The ATD is rocked from side-to-side and allowed to sit for 5 minutes in order to fully 

settle into the seat. This settling time is necessary for any slow recovery type foam to fully contour to the 

pelvis or buttocks of the ATD.

A three dimensional measuring machine was used to record the ATD head center of gravity photometric target, as well as the hip point and vertical pelvis targets. These measurements were used to derive the 

torso and pelvis angle. The hip point, or H-Point, lies on a line passing through the center of both hip 

ball/socket joints of the ATD. For these tests, target markers centered on this line were placed on the surface of the pelvis. The origin selected for the seating was the intersection of the rigid seat pan and seat back, 

which could be easily located on both the rigid test seat and the wooden surrogate.
3

Figure 2. FAA Hybrid III on Wooden 1 G Seating Fixture

The 1-G position data were then used to place the ATD in the correct fore-aft and vertical position in 

the pitched up rigid seat, with tolerances of ± 0.1 inch for the pelvis hip point, ± 1° for the pelvis angle, and 

± 2° for the torso angle. Achieving this initial position required insertion of a cloth covered closed cell foam 

shim behind the ATD to maintain the fore-aft position and significant tension in the lap belt to maintain the 

vertical position. Note that in some tests, this tolerance on position was exceeded somewhat. This was due 

to the stress-relieving properties of this type of cushion foam, which made it very difficult to achieve and 

maintain an exact pelvis position. 

Test Set Up

To evaluate occupant response at multiple loading rates, triangular shaped impact pulses with peak G of 

14 G and 19 G were chosen (Figure 3). These test severities correspond to the combined horizontal/vertical 

tests specified in 14 CFR 25.562 and 23.562 [1]. A rigid seat test fixture with its horizontal (aircraft longitudinal) axis pitched up 60° with respect to the sled horizontal was used in order to eliminate as much variability as possible in the test set up (Figure 4). This seat had a seat back with an angle of 13° with respect to the 

aircraft vertical and a flat seat pan with an angle of 5° with respect to the horizontal. The seat pan was 16 

inches wide and 15.5 inches long from the front edge to the intersection of the pan and back planes. The 

simulated floor was adjusted so that the distance between the H-Point and the center of the ankle was the 

same as the 1-G seated position, approximately 13 inches.
4

Figure 3. Ideal 14 and 19 G acceleration pulses

Figure 4. Rigid Seat Pitched up at 60°

Instrumentation

Electronic instrumentation. The ATD and rigid seat were instrumented as shown in Table 1. For this project, the seat pan and foot rest were instrumented with load cells to evaluate the manner in which the ATD 

loads into the rigid seat. The test data were gathered and filtered per the requirements of SAE J211-1 [5].

The sign convention of the recorded signals conformed to SAE J1733 [6].

0

2

4

6

8

10

12

14

16

18

20

0 20 40 60 80 100 120 140 160

Acceleration (G)

Time (ms)

14 G

19 G
5

Table 1. Instrumentation List

Ch. Number Description Filter 

Class Range Units

1 Sled Acceleration 60 25 G

2 Aux Sled Acceleration 60 25 G

4 Foot Rest Plate Acceleration 60 25 G

5 Lumbar Fx 600 3000 lb

6 Lumbar Fy 600 3000 lb

7 Lumbar Fz 600 5000 lb

8 Lumbar Mx 600 10000 in-lb

9 Lumbar My 600 10000 in-lb

10 Lumbar Mz 600 4000 in-lb

21 Thorax Ax 600 2000 G

22 Thorax Ay 600 2000 G

23 Thorax Az 600 2000 G

24 Thorax Rx ARS12K 180 12000 Deg/Sec

25 Thorax Ry ARS12K 180 12000 Deg/Sec

26 Thorax Rz ARS12K 180 12000 Deg/Sec

27 Thoracic Fx 600 3000 lb

28 Thoracic Fy 600 3000 lb

29 Thoracic Fz 600 4500 lb

30 Thoracic Mx 600 5000 in-lb

31 Thoracic My 600 8000 in-lb

32 Pelvis Ax 600 500 G

33 Pelvis Ay 600 500 G

34 Pelvis Az 600 500 G

35 Pelvis Rx ARS12K 180 12000 Deg/Sec

36 Pelvis Ry ARS12K 180 12000 Deg/Sec

37 Pelvis Rz ARS12K 180 12000 Deg/Sec

51 Seat Pan Load Cell Fx 60 10000 lb

52 Seat Pan Load Cell Fy 60 10000 lb

53 Seat Pan Load Cell Fz 60 10000 lb

54 Seat Pan Load Cell Mx 600 25000 in-lb

55 Seat Pan Load Cell My 600 25000 in-lb

56 Seat Pan Load Cell Mz 600 25000 in-lb

57 Foot Rest Load Cell Fx 60 10000 lb

58 Foot Rest Load Cell Fy 60 10000 lb

59 Foot Rest Load Cell Fz 60 10000 lb

Video coverage. High-speed (1000 frames per second), high resolution (1024 x 768 pixels) color video was 

captured from each side by cameras aimed perpendicular to the sled. Targets were placed on the ATD at the 

head center of gravity, the side of the pelvis at the hip joint, two auxiliary hip point locations, and on a rigid 

plate mounted to the knee joint. Targets were also placed on rigid structure for scaling and for subtracting 

relative motion between the sled and the camera. The positions of selected targeted points were measured 
6

initially with a measuring arm and derived during the test from the videos using procedures complying with 

the requirements of SAE J211-2 [7]. The relative accuracy of the tracked point locations, calculated per SAE 

J211-2 in this test series, ranged from 0.01 inch to 0.08 inch from their actual location. One target of interest, the H-point target marker, tended to move with respect to the internal pelvis structure due to flexure of 

the external flesh in that area as loading was applied. For this reason, the H-point (structural) location was 

derived from the tracked locations of other target markers on the pelvis that did not move relative to the 

internal pelvis structure. The accuracy of this virtual point is related to the accuracy of the referenced targets 

and their relative locations to the virtual point. In this case, it ranged from 0.02 to 0.16 inch from the actual 

location.

Restraint

A standard 2-point lap belt was used to restrain the ATD as well as hold the ATD in the nominal 1-G 

seating position. The belt anchors were 5.18 inches forward and 0.11 inch above the pan/back intersection.

This location is further forward than typical for aircraft seats, but was chosen to facilitate observation of 

pelvis motion and to provide a means to maintain the necessary initial ATD preload into the cushion.

Cushion

ConforTM foam comes in four different degrees of stiffness and is color coded to avoid confusion. The 

two mid-stiffness foams, CF-42 (pink) and CF-45 (blue), were selected for this evaluation because they are 

the most commonly used types in aviation seats (Figure 5). The original formulation foam materials, which 

are no longer produced, were supplied from CAMI stock. The AC formulation foams were supplied by the 

foam distributor, Skandia Inc. All test articles of a particular type were cut from the same roll of material to 

maximize consistency between the articles. The articles were 18 inches wide and 16 inches long. Each article 

was held to the rigid seat pan by a tight fitting cloth cover.

Ten of the 18 tests were conducted using pink cushions, and of these 10, six were the AC foam in 

thickness of two and four inches, and four were the original formulation in thickness of two and four inches, see the test matrix in Table 2. The other eight tests were conducted with the blue foam, where each version and thickness was tested twice, once at each acceleration level. Due to scarcity of the original formulation foam, it was necessary to use some articles more than once. Since only the aft one-third of the cushion 

is loaded significantly by the ATD, turning the articles ensured that the area loaded had not been compressed during a previous test. Those articles were rotated 180° for the second test, rotated 90° and turned 

over for the third, and rotated 180° for the fourth.

Figure 5. CF-42 (Pink) Left and CF-45 (Blue) Right ConforTM foams
7

Data Processing

The lumbar loads were gathered and filtered using CFC 600, and normalized to the test goal G-peak as 

allowed in AS8049B [8]. This procedure adjusts the recorded lumbar load value by multiplying it by the ratio 

of the goal acceleration divided by the measured peak acceleration. Seat pan and foot rest loads were tare 

corrected to eliminate the inertial effect of the fixture and internal load cell mass.

Test Matrix

Table 2 summarizes the variables evaluated for each test in this study. These include the cushion thickness in inches, cushion version (whether it is AC or original), and the goal peak G for the test, and the cushion color. Because of the efficiency of CAMI’s servo sled system, it is possible to conduct simple tests like 

these in rapid succession. However, to provide the ATD elastomeric components sufficient time to recover 

to a nominal state, the ATD was situated such that no vertical load acted on the pelvis and spine for a minimum of 20 minutes between tests. Additionally, the time from when the ATD was positioned to match the 

1-G seating to the time that the test was run was approximately 10 minutes, which allowed for the compressed seat cushion foam to stress relieve. This estimated time includes taking measurements, pre-test still 

photos, calibrating the data acquisition system, and charging the servo-sled. 

Table 2. Test Matrix

Thickness (in) Version Goal G Cushion Color Test Number

2 Original 14 Blue A15005

2 Original 14 Pink A15007

2 Original 19 Pink A15001

2 Original 19 Blue A15003

2 AC 14 Blue A15006

2 AC 14 Pink A15008

2 AC 19 Pink A15002

2 AC 19 Blue A15004

4 Original 14 Blue A15018

4 Original 14 Pink A15019

4 Original 19 Blue A15014

4 Original 19 Pink A15016

4 AC 14 Blue A15017

4 AC 14 Pink A15020

4 AC 19 Blue A15013

4 AC 19 Pink A15015

4 AC 19 Pink A15021

4 AC 19 Pink A15022

RESULTS

Initially the FAA Hybrid III was measured on the wooden seat without any cushion to get the nominal 

1-G H-point height. The ATD was then seated on each cushion and a 1-G measurement was recorded. Table 3 summarizes the cushion compression for the test articles. Row 1 shows the nominal value for the FAA 

Hybrid III H-point height on a bare seat with a seat pan at 5°. The remaining rows show the heights for 
8

each cushion. The initial cushion compression is the cushion thickness less the difference between the nocushion H-point height and the H-point height on the cushion. The H-point position was measured by photometrics during the dynamic test. These data were used to determine the maximum vertical (along z-axis) 

distance the pelvis traveled into the cushion relative to its initial pre-test position.

Table 3. Compression Summary

Thickness Version Cushion 

Color

Goal 

G

H-Point Height

at 1-G

(in)

Initial Cushion Compression

(in)

H-Point Z 

max motion 

(in)

N/A N/A No Cushion N/A 3.86 N/A N/A

2.0 Original Pink 14 4.83 1.03 0.9

2.0 AC Pink 14 4.76 1.10 0.7

2.0 Original Pink 19 4.82 1.04 0.8

2.0 AC Pink 19 4.76 1.10 0.8

2.0 Original Blue 14 5.01 0.85 0.7

2.0 AC Blue 14 5.20 0.66 0.9

2.0 Original Blue 19 5.01 0.85 0.8

2.0 AC Blue 19 4.97 0.89 1.0

4.0 Original Pink 14 6.13 1.73 1.7

4.0 AC Pink 14 6.07 1.79 1.8

4.0 Original Pink 19 6.10 1.76 2.3

4.0 AC Pink 19 5.84 2.02 1.9

4.0 Original Blue 14 7.35 0.51 2.3

4.0 AC Blue 14 7.13 0.73 2.0

4.0 Original Blue 19 7.19 0.67 2.5

4.0 AC Blue 19 7.12 0.74 2.4

The lumbar load time-history produced in the tests of the 4-inch thick cushions is provided in Figure 6.

As can be seen in Figure 3, the 19 G acceleration onset rate is nearly twice the 14 G rate. Figure 6 shows 

that lumbar loading rates are clearly related to sled acceleration onset rate with the 19 G tests producing 

loading rates that are at least twice the rates seen in the 14 G tests. For both loading levels, the AC pink 

cushions exhibited a slightly higher loading rate than the original pink formulation, while the loading rate for 

the blue cushions was nearly identical. Loading rate differences are of interest because the rate of spinal 

loading can affect the type and severity of spinal injuries produced [9]. 
9

Figure 6. Lumbar Load Time History

To compare the dynamic force/deflection response for each 4-inch thick cushion, the vertical position 

of the ATD hip point was plotted against the tare corrected seat pan vertical load. (Figures 8 and 10) The 

motion shown in these plots is a combination of the ATD pelvis and the cushion dynamic compliance.

Since the pelvis contribution should be similar for all tests at a given load, the data should be useful for 

comparison of the foam dynamic response. Note the load magnitude shown does not reflect the initial 1 G 

preload into the cushion, which is approximately 130 lb. 

Blue ConforTM

The blue ConforTM original and AC formulation foams were evaluated at two test severities and two 

thicknesses, for eight tests total (Table 4 and Figure 7). At 14 G, the 2-inch, AC formulation cushion had a 

10 lb lower normalized lumbar load than the original formulation. At 19 G, the 2-inch, AC formulation’s 

lumbar load was 95 lb more. At both 14 G and 19 G, the 2-inch AC cushions produced a difference in vertical H-Point Z motion that was 0.2 inch more than the original. At 14 G, the 4-inch, AC formulation cushion lumbar load was14 lb more than the original formulation, and at 19 G, the AC formulation produced 44 

lb less lumbar load than the original formulation. At 14 G, the AC cushion had 0.3 inch less vertical pelvis 

excursion than the original cushion, and at 19 G the AC excursion was 0.1 inch less than the original. 
10

Table 4. Blue ConforTM Summary

Test Parameter Test Number

Blue A15005 A15006 A15003 A15004 A15018 A15017 A15014 A15013

Cushion Thickness 

(in) 2 2 2 2 4 4 4 4

Version Original AC Original AC Original AC Original AC

Goal H-Point Z (in) 5.05 5.09 5.05 5.09 7.40 7.18 7.40 7.18

Achieved H-Point Z 

(in) 5.01 5.20 5.01 4.97 7.35 7.13 7.19 7.12

Goal Pelvis Angle 

(°) -10.1 -10.0 -10.1 -10.0 -9.4 -9.5 -9.4 -9.5

Achieved Pelvis

angle (°) -10.3 -8.5 -10.2 -9.6 -10.5 -10.4 -10.1 -9.9

Impact Velocity 

(ft/s) 35.3 35.3 33.8 33.5 35.3 35.3 33.7 33.4

Impact Acceleration (G) 14.5 14.4 19.4 19.3 14.4 14.6 20.4 19.1

Normalized Lumbar 

Load Fz (lb) 970 960 1509 1604 956 970 1514 1470

Seat Pan Fz (lb) 1968 2019 3074 3270 2166 2242 3230 2981

Foot Rest Fz (lb) 706 711 962 989 801 797 1161 1047

H-Point Z max motion (in) 0.7 0.9 0.8 1.0 2.3 2.0 2.5 2.4

Figure 7. Blue ConforTM

Figure 8 shows a comparison of the H-Point vertical position for the 4-inch original and AC blue foam 

cushions at the 14 G and 19 G peak accelerations. These plots characterize the combined dynamic 

force/deflection response of the bottom of the ATD pelvis and the cushion. The original and AC foams 

had very similar response throughout the test at the 19 G loading level. Although the response initially dif-
11

fered for the foams at the 14 G load level, once the pelvis position reached about 6.5 inches, the responses 

merged and nearly overlaid throughout the rest of the test. The initial difference in the 14 G tests was due to 

a 0.22 inch higher initial position of the pelvis in the original blue test vs. the AC blue test. This graph also 

illustrates the effect that loading rate has on both the original and AC formulations of this foam. The F/D 

response for the 19 G loading level is stiffer than for the 14 G loading level up to 1250 lb, after which the 

response is similar; the slope of the F/D curves are nearly parallel.

Figure 8. Blue ConforTM H-Point vertical position with respect to Pan/Back intersection for 4” thickness 

at 14 G and 19 G peak acceleration

Pink ConforTM

The pink ConforTM foam original and AC formulations, which are less stiff foam than the blue, were 

evaluated using the same eight configurations used for the blue tests (Table 5). The 4-inch thick AC formulation cushion was tested a total of three times at 19 G. Figure 9 shows a bar chart summarizing the normalized peak lumbar load produced by the original and AC pink foams at 14 and 19 G respectively. Only the 

first of the three repeated 19 G tests, number A15015, is shown. At 14 G the 2-inch, AC formulation cushion produced a normalized lumbar load that was 65 lb more than the original cushion test. At 19 G, the 2-

inch, AC formulation produced 34 lb less than the original cushion. At 14 G the 2-inch, AC formulation’s 

vertical pelvis excursion was 0.2 inch less than the original, and at 19 G the excursions were about the same.

At 14 G, the 4-inch, AC formulation lumbar load was 53 lb more than the original, at 19 G the AC formulation was 191 lb more. At 14 G, the 4-inch AC formulation’s vertical pelvis excursion was 0.1 inch more than 

the original, and at 19 G the AC was 0.4 inch less.
12

Table 5. Pink ConforTM

Test Parameter Test Number

Pink A15007 A15008 A15001 A15002 A15019 A15020 A15016 A15015 A15022 A15021

Cushion Thickness 

(in) 2 2 2 2 4 4 4 4 4 4

Version Original AC Original AC Original AC Original AC AC AC

Goal H-Point Z (in) 4.88 4.74 4.88 4.74 5.98 5.92 5.98 5.92 5.92 5.92

Achieved H-Point Z 

(in) 4.82 4.76 4.83 4.66 6.13 6.07 6.10 5.84 5.84 6.00

Goal Pelvis Angle 

(°) -12.5 -12.5 -12.5 -12.5 -13.5 -15.7 -13.5 -15.7 -15.7 -15.7

Achieved Pelvis 

Angle (°) -11.8 11.5 -11.6 -11.3 -12.1 -14.7 -12.8 -15.2 -14.3 -13.7

Impact Velocity 

(ft/s) 35.3 35.2 33.3 32.9 35.7 35.4 33.2 33.4 33.4 33.4

Impact Acceleration (g) 14.5 14.2 19.4 19.2 14.5 14.5 19.4 19.4 19.4 19.4

Normalized Lumbar Load Fz (lb) 983 1048 1694 1660 1100 1153 1771 1962 1975 1951

Seat Pan Fz (lb) 2048 2108 3695 2960 2318 2413 3581 3692 3695 3590

Foot Rest Fz (lb) 767 777 1165 1075 846 869 1135 1289 1165 1216

H-Point Z max 

motion (in) 0.9 0.7 0.8 0.8 1.7 1.8 2.3 1.9 1.8 1.9

Figure 9. Pink ConforTM

Figure 10 shows a comparison of the H-Point vertical position for the 4-inch original and AC pink 

foams for the 14 G and 19 G peak accelerations. These plots characterize the combined dynamic 
13

force/deflection response of the bottom of the ATD pelvis and the cushion. The original and AC foams 

had very similar response throughout the test at the 14 G loading level. Although the response was initially 

less stiff for the AC foam at the 19 G load level, after the pelvis position reached 4.3 inches, the stiffness 

surpassed the original foam response. The initial difference in the 14 G tests was due to a 0.26 inch lower 

initial position of the pelvis in the AC pink test vs. the original pink test. The rate of loading does not appear 

to affect the response of the original foam since the F/D response was similar for both the 14 and 19 G 

tests. The loading rate did appear to increase the rate of stiffness change for the AC foam at 19 G compared 

to the 14 G test, although that could be in part attributable to the difference in cushion initial compression.

Overall, these results indicate that the AC pink ConforTM was both a little stiffer than the original formulation and more rate sensitive.

Figure 10. Pink ConforTM Force Deflection curve for 4” thickness at 14 G and 19 G peak acceleration

Test Repeatability

One of the test conditions was run two more times to evaluate test repeatability in this test series. The 

test condition selected was the AC formulation, 4-inch thick pink ConforTM foam at the 19 G severity. This 

condition was selected because variability generally increases with lumbar load magnitude [4], and this test 

condition produced the highest lumbar load of the series. The difference between these 3 repeated tests was 

less than 25 lb, with a standard deviation of only 12 lb. The force-deflection response was also very similar 

for these three tests as shown in Figure 11. The third test F/D curve was offset from the others due to a 

small difference in initial seated height but was otherwise very similar to the other two tests. Coupled with 

the observation in reference 4, these data suggest that the error on the lumbar load data in this report has an 
14

upper bound of ±1.3%, based on 2 standard deviations from the mean. This error accounts for repeated 

cushion tests with the same test article and a single ATD and may only be applicable to this test series.

While the error bound includes the variability in the test methodology with tightly controlled seating parameters, it does not include the cushion variability, ATD-to-ATD variability, or lab reproducibility.

Figure 11. Pink ConforTM Force Deflection curve for 4” thickness at 19 G peak acceleration - 3 repeated tests

DISCUSSION

The results showed that for each material formulation, cushion thickness, and impact level, the blue type 

foam produced lower lumbar loads than the pink type. However, the results yielded no clear trend for material formulation or thickness, i.e. the AC foams did not always produce higher lumbar load than original, and 

thicker cushions did not always produce higher lumbar loads. Specifically, the blue AC formulation produced lumbar loads between 2.9% less and 6.4% greater than the original version. The pink AC formulation 

produced lumbar loads between 2.0% less and 10.8% greater than the original version.

All of the 14 G tests produced lumbar loads that were significantly less than the 1500 lb limit and had 

minimal variation in load between the original and AC formulation foams. All of the 19 G tests produced 

lumbar loads that were near to, or significantly exceeded the 1500 lb regulatory injury limit. This means that 

the loads applied in that test condition are greater than what would occur during successful qualification 

tests of a real seat. Since lumbar load variability appears to be related to peak load, it would be expected that 

the variation between the original and AC cushions would be less than what was measured during this pro-
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ject if the 19 G test condition was reduced to ensure all produced loads were below 1500 lb. This should be 

considered when evaluating reported lumbar load differences.

These tests were conducted with a single ATD, and while good repeatability was achieved, the lack of 

ATD dynamic vertical calibration standards means that repeating these tests with a different ATD could 

result in different results. The Hybrid III pelvis used for this series must meet a specific compressed height 

requirement, ±0.07 inch, versus a ±0.2 inch requirement for the Hybrid II, which should control vertical 

performance variation between test dummies, somewhat. However, development and implementation of a 

vertical dynamic calibration method for ATDs used in aviation tests would be the best way to ensure an acceptable level of reproducibility. For basic material comparisons, dynamic tests with a high-rate load frame 

would have the advantage of eliminating all ATD variability.

Another factor to consider when comparing the reported lumbar loads is that this project did not attempt to quantify the effect that normal production variability in foam characteristics has on dynamic performance. While the test articles were cut from single layers of foam to reduce variation, how those articles 

compare to other foam buns or even other layers within the same bun is unknown.

In addition to lumbar load, when changing the design of a seat cushion used on a dynamically qualified 

seat, one concern is whether the AC cushion will raise the initial position of the occupant significantly, affecting the seat overturning moment during horizontal loading or HIC compliance. For the tested configuration (a flat rigid seat pan), there was very little difference in initial 1 G seated height between the original 

and AC formulations for both types and thicknesses examined. The difference ranged from 0.22 inch lower 

ATD H-point height for the 4-inch thick blue foam to 0.04 higher for the 2-inch thick blue foam. Policy 

memo ANM-115-05-005 allows for a 0.5 inch difference in seated height when replacing monolithic cushions [10].

LIMITATIONS

Due to limited availability of test articles, each formulation was only tested once at each peak G level.

The repeated case with the pink ConforTM only utilized one sample, which was rotated and flipped to expose different areas. The uncertainty due to this limited sample is mitigated somewhat by the excellent 

measured repeatability for the case expected to produce the highest variability. The scope of the project and 

the availability of test articles prevented an evaluation of that effect that production variability could have on 

dynamic material characteristics and lumbar load.

This scope of this project did not include investigating differences in flammability between the original 

and AC foams, which may also have been affected by the formulation change.

CONCLUSION

Dynamic tests of the original and AC ConforTM formulations produced similar lumbar loads for two 

types, CF-42 (pink) and CF-45 (blue) and two thicknesses at the 14 G acceleration levels. At the 19 G level, 

lumbar loads for the original and AC foams diverged some, but the largest difference in peak lumbar load 

produced by the AC version was 11% greater for pink ConforTM and 6% greater for blue ConforTM. If some 

level of production variability is assumed, then these values suggest that there may not be a significant difference between the impact performance of the original and AC formulation for aircraft bottom seat cushion applications. Since the three formulations (Standard, M, and AC) look similar, and it is possible that not 

all distributors have revised their part numbers to reflect the formulation change, end users should ensure 

that the correct formulation is obtained for aviation seating systems, and that the flammability performance 

is suitable for their specific application.
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REFERENCES

1. U.S. Code of Federal Regulations, Title 14 Parts, 23.562, 25.562, 27.562, 29.562. Washington, DC: US 

Government Printing Office.

2. Product Bulletin 175: ConforTM Foam Family, Aearo Technologies LLC, Indianapolis, IN, 2013.

3. Gowdy V, DeWeese R, Beebe M, Wade B, Duncan J, Kelly R, Blaker J. A Lumbar Spine Modification 

to the Hybrid III ATD For Aircraft Seat Tests. Warrendale, PA: SAE International, 1999.

4. Moorcroft D, DeWeese R, and Taylor A, "Improving Test Repeatability and Methods," The Sixth 

Triennial International Fire & Cabin Safety Research Conference, Oct 25-28, 2010.

5. SAE International. Instrumentation for Impact Test – Part 1- Electronic Instrumentation. Warrendale, 

PA: SAE International; Surface Vehicle Recommended Practice No: J211-1. 2014.

6. SAE International. Sign Convention for Vehicle Crash Testing. Warrendale, PA: SAE International; 

SAE Surface Vehicle Information Report No: J1733. Dec. 1994.

7. SAE International. Instrumentation for Impact Test – Part 2- Photographic Instrumentation. Warrendale, PA: SAE International; SAE Surface Vehicle Recommended Practice No: J211-2. 2014.

8. SAE International. SAE AS8049 Rev B, “Performance Standard for Seats in Civil Rotorcraft, Transport 

Aircraft, and General Aviation Aircraft,” 2005.

9. Tran NT, Watson NA, Tencer AF, Ching RP and Anderson PA, “Mechanism of the burst fracture in 

the thoracolumbar spine: the effect of loading rate,” Spine 20:1984-1988, 1995.

10. FAA policy statement, ANM-115-05-005, “Policy Statement on Acceptance of a Component Method to 

Demonstrate Compliance with § 25.562(c)(2) for replacement seat bottom Cushions.” DOT/Federal 

Aviation Administration, Washington, DC. 2005.