Subject: DYNAMIC TESTING OF PART 23 Date: 6/22/89 AC No: 23.562-1 AIRPLANE SEAT/RESTRAINT SYSTEMS Initiated By: ACE-100 Change:
AND OCCUPANT PROTECTION
1. PURPOSE. This advisory circular (AC) provides information and guidance regarding acceptable, but not the only, means of compliance with Part 23 of the Federal Aviation Regulations (FAR) applicable to dynamic testing of airplane seats. This material is neither mandatory nor regulatory in nature.
2. RELATED REGULATIONS. Sections 23.562, 23.785, 23.787.
3. RELATED READING MATERIAL.
a. Code of Federal Regulations (CFR), 49 CFR 572, Chapter 5, Subpart B - Anthropomorphic Test Dummies (ATD).
b. Aircraft Crash Survival Design Guide, (Volumes I-V), Simula, Inc., USARTL-TR-79-22(A-E), Applied Technology Laboratory, U.S. Army Research and Technology Laboratories (AVRADCOM), Fort Eustis, Virginia, 23604, 1980.
c. Coltman, Joseph W., Design and Test Criteria for Increased Energy- Absorbing Seat Effectiveness, FAA-AM-83-3, Federal Aviation Administration, March 1983.
d. Injury Criteria for Human Exposure to Impact, Advisory Circular 21-22, Federal Aviation Administration, June 20, 1985.
e. "Motor Vehicle Instrument Panel Laboratory Impact Test Procedure Head Area - SAE J921b," SAE Recommended Practice, 1979 SAE Handbook, Vol. 2, pp. 34.133-34.134, Society of Automotive Engineers, Inc., 1979.
f. "Instrumentation for Impact Tests - SAE J211b," SAE Recommended Practice, 1979 SAE Handbook, Volume 2, pp. 34.117-34.118, Society of Automotive Engineers, Inc., 1979.
4. BACKGROUND.
a. Dynamic Test Methods. This AC focuses on the use of dynamic test methods for evaluating the performance of airplane seats, restraint systems, and related interior systems for demonstrating structural strength and the ability of those systems to protect an occupant from serious injuries sustained in a crash environment. These methods differ from static test
methods, which are limited to demonstrating only the structural strength of the seat or restraint system. This AC describes the dynamic test procedures and provides some insight into the logic behind these procedures. It also defines the test facility and equipment characteristics necessary for conducting these tests.
b. Standardized Test Methods. Dynamic tests are often accomplished at facilities other than those of the designer or fabricator of the test article. To obtain consistent test results, it is necessary to specify the critical test procedures in detail, and then carefully follow these procedures when conducting the tests. This AC defines certain critical procedures for accomplishing the tests of the restraint systems and assessing the data obtained from the tests. Many of these procedures are already accepted as standards by government and commercial test facilities and have been modified only as necessary for the specific testing of civil airplane systems.
c. Relation of Dynamic Tests to Design Standards. This AC describes test procedures which provide a means of showing compliance with the FAR and are useful in assessing the performance of an airplane seat, restraint system, and interior system. It is impractical to conduct sufficient tests for assessing the performance of the system throughout its entire range of desirable performance.
The seat, restraint, and related interior system should be designed for the range of occupants and environments for which it is expected to perform, not just for the dynamic test conditions described in this AC.
5. DEFINITIONS.
a. Dynamics Terms.
(1) Dynamic Overshoot. The amplification of loads or accelerations transmitted to occupants or structure during impact. This amplification is the result of the dynamic response of the system. When dealing with impact injury prevention, the occupant should be considered an element of the system.
(2) Rebound. Rapid return toward the original position upon release, or rapid reduction of the deforming load, usually associated with elastic deformation.
(3) Dynamic Response. The motion or other output of a device or system resulting from a time varying excitation produced under specified conditions.
b. Seat Design Terms.
(1) Energy-Absorber (Load Limiter). A device or structure used to limit the transmitted load to a preselected level. These devices, also referred to as energy absorbers or energy attenuators, control load levels by applying a resistive force over a deformation distance without significant elastic rebound.
(2) Bottoming. The exhaustion of available stroking distance or deformation accompanied by an increase in force, e.g., when a seat stroking in the vertical direction uses all the available stroking distance or deformation and impacts the floor, or when a soft seat cushion compresses against a hard support structure.
(3) Seating/Restraint System. A system that includes the seat, the cushions, the safety belt, the shoulder harness (upper torso restraint), and the attachment devices.
c. Occupant-related Terms.
(1) Human Body Coordinate System. To help define vectors of displacement, velocity, acceleration, or force relative to the occupant, the coordinate system shown in figure 1 is often used. Although this coordinate system is not universally accepted, it is used in much of the literature discussing human tolerance.
(2) Submarining. Rotation of the pelvis under and about the safety belt, often accompanied by safety belt slippage up and over the iliac crests. This may result in undesirable occupant forward motion relative to the seat and in internal or spinal column injuries.
6. DYNAMIC TEST METHODS AND FACILITIES.
a. General. A minimum of two dynamic tests are required to assess the performance of an airplane seat, restraint system, and related interior system.
The seat, the restraint, and the nearby interior should all function together as a system to provide protection to the occupant during a crash. One of the tests (Test 1) determines the protection provided when the crash environment is such that a predominant impact load component is directed along the spinal column of 3
the occupant, in combination with a forward component. Protection against spinal injury is important under these conditions, and it may be necessary to provide energy absorbing (load limiting) capability in the seat to be able to satisfy the human injury criteria specified in § 23.562(c) (7). The other test (Test 2) evaluates the protection provided in crashes where the predominant impact is in the longitudinal direction, in combination with a lateral component. Evaluation of head injury protection is important in this test if the head is allowed to strike some interior portion of the airplane, or a seat and restraint seat forward of the occupant. This test is also a significant test of the structural strength of the Both tests provide the opportunity for assessing submarining (where the seat belt slips above the pelvis) and roll out of the torso restraint system (of particular concern with some single diagonal torso restraint belts). Since external crash forces frequently cause structural deformations, simulated floor or sidewall deformation is used to show that the seat can accommodate the relative deformation between the seat and the floor and still function without imposing excessive loads on the seat, the floor attachment fittings or floor tracks.
specific test conditions are shown in figure 2.
Illustration shows a Test 1 (§ 23.562(b)(1))| Test 2 (§ 23.562(b) | forward facing seat.
Dummy inertial load shown by arrow:
‡10° Crew Passenger Crew Passenger Min. Vi, fps 31 31 42 Max. tr, sec. 0.05 0.06 0.05 0.06 Min. G 19 15 26 21 Deform floor:
degrees roll none none 10 10 degrees pitch required required 10 10 time deceleration G - deceleration measured on test tr = rise time G fixture or sled near Vi = Impact Velocity the seat position.
Figure 2 - SEAT/RESTRAINT SYSTEM DYNAMIC TESTS
NORMAL, UTILITY, OR ACROBATIC CATEGORY AIRPLANES
b. Test Facilities. There are a number of test facilities which can be used to accomplish dynamic testing. These can be grouped into categories based on the method they use to generate the impact pulse, i.e., accelerators, decelerators, or impact with rebound, and whether the facility is a horizontal (sled) design or a vertical (droptower) arrangement. Each of the designs has characteristics which have advantages or disadvantages with regard to the dynamic tests discussed in this AC. One concern is the rapid sequence of acceleration and deceleration which may take place in the tests. In an airplane crash, the acceleration phase is always gradual, and usually well separated in time from the deceleration (crash) phase. In a test, the deceleration always closely follows the acceleration. When assessing the utility of a facility for the specific test procedures outlined in the recommendations, it is necessary to understand the possible consequences of this rapid sequence of acceleration and deceleration.
(1) Deceleration Sled Facilities. In an airplane crash, the impact takes place as a deceleration, so loads are applied more naturally in test facilities which create the test impact pulse as a deceleration. Since it is simpler to design test facilities to extract energy rather than to impart energy in a controlled manner, several different deceleration sled facilities can be found.
The deceleration sled facility at the Federal Aviation Administration's Civil Aeromedical Institute (CAMI) was used in developing the test procedure discussed in this AC. The facility performed satisfactorily in those tests. The acceleration phase of the test, where sufficient velocity for the test impact pulse is acquired, can distort the test results if the acceleration is so high that the test articles or anthropomorphic test dummies are moved from their intended pre-test position. This inability to control the initial conditions of the test would directly affect the test results. This can be avoided by using a lower acceleration for a relatively long duration and by providing a coast phase (in which the acceleration or deceleration is almost zero) prior to the impact.
This allows any dynamic oscillation in the test articles or the test dummy, which might be caused by the acceleration, to decay. To guard against errors in data caused by pre-impact accelerations, data from the electronic test measurements (accelerations, loads) should be reviewed for the time period just before the test impact pulse to make sure all measurements are at the baseline (zero) level.
Photometric film taken of the test should also be reviewed to make certain that the anthropomorphic test dummies used in the test and the test articles are all in their proper position prior to the test impact pulse. The horizontal test facility readily accommodates forward facing seats in both tests discussed in this AC, but problems can exist in positioning the test dummies in Test 1 if the seat is a rearward facing or side facing seat. In these cases, the test dummies tend to fall out of the seat due to the force of gravity and can be restrained in place using break-away tape, cords, or strings. Since each installation may present its own problems, there is no simple, generally applicable, guidance which can be given for doing this. However, the sled facility should conduct some preliminary impact tests to ensure that the conditions shown in figure 2 can be met and the results included in the test reports described in paragraph 8. Attention should be given to positioning the test dummy against the seat back and to proper positioning of the test dummy's arms and legs. It may be necessary to build special supports for the break-away restraint so that they do not interfere with the function of the seat and restraint system during the test. Film taken of the test should be reviewed to make sure that the break-away restraint did break (or become slack) in a manner that did not influence the motion of the test dummy or the test articles.
(2) Acceleration Sled Facilities. Acceleration sled facilities, usually based on the HYdraulically controlled Gas Energized (HYGE) accelerator device, provide the impact test pulse as a controlled acceleration at the beginning of the test. The test item and the test dummies are installed facing in the opposite direction from the velocity vector, opposite from the direction used on a deceleration facility, to compensate for the change in direction of the impact.
There should be no problem with the test dummies or the test items being out of position, since there is no sled movement prior to the impact test pulse. After the impact test pulse, when the sled is moving at the maximum test velocity, it should be safely brought to a stop. Most of the facilities of this design have limited track length available for deceleration, so that the deceleration levels can be relatively high and deceleration may begin immediately after the impact test pulse. Since the maximum response of the system usually follows (in time) the impact test pulse, any sled deceleration which takes place during that response may affect the response and change the test results. The magnitude of change depends on the system being tested, so that no general "correction factor" can be specified. The effect can be minimized if the sled is allowed to coast, without significant deceleration, until the response is complete. If the seat or restraint system experiences a structural failure during the test pulse, the post-impact deceleration can increase the damage and perhaps result in failures of unrelated components. This may complicate the determination of the initial failure mode and make product improvement more difficult. One other consideration is that the photometric film coverage of the response to impact test pulse should be accomplished when the sled is moving at near maximum velocity. On-board cameras or a series of track side cameras are usually used to provide film coverage of the test. Since on-board cameras frequently use wide angle lens placed close to the test items, it is necessary to account for the effects of distortion and parallax when analyzing the film. The acceleration sled facility faces the same problems in accommodating rearward facing or side facing seats in Test 1, as the deceleration sled facility, and the corrective action is the same for both facilities.
(3) Impact-with-Rebound Sled Facilities. One other type of horizontal test facility used is the "impact-with-rebound" sled facility. On this facility, the impact takes place as the moving sled contacts a braking system which stores the energy of the impact, and then returns the stored energy back to the sled, causing it to rebound in the opposite direction. This facility has the advantage over acceleration or deceleration facilities in that only one half of the required velocity for the impact would need to be generated by the facility (assuming 100 percent efficiency). Thus the track length can be shortened and the method of generating velocity is simplified. The disadvantages of this facility combine the problems mentioned above for both accelerator facilities and decelerator facilities. Since one of the reasons for this type of facility is to allow short track length to be used, it may be difficult to obtain sufficiently low acceleration just before or after the impact pulse to resolve data error problems caused by significant pre-impact and post-impact accelerations.
(4) Drop Towers. Vertical test facilities can include both drop towers (decelerators) and vertical accelerators. Vertical accelerators which can produce the long duration/displacement impact pulse discussed in this AC have not been generally available. However, drop towers are one of the easiest facilities to 6
build and operate, and are frequently used. In these facilities, the pull of earth's gravity is used to accelerate the sled to impact velocity so that the need for a complex mechanical accelerating system is eliminated. Unfortunately, these facilities are difficult to use for conducting Test 2, particularly for typical forward facing seats. In preparing for this test, the seat should be installed at an angle such that the anthropomorphic test dummies tend to fall from the seat due to gravity. The restraint system being tested cannot hold the test dummy against the seat unless tightened excessively and does not usually locate the head, arms, or legs in their proper position relative to the seat. Design and fabrication of an auxiliary "break-away" dummy positioning restraint system just for this test is a complex task. The auxiliary restraint should not only position the test dummy against the seat (including maintaining proper seat cushion deflection) during the pre-release condition of one g, it should also maintain the test dummy in that proper position during the free fall to impact velocity when the system is exposed to zero g, and then it should release the test dummy in a manner which does not interfere with the test dummy's response to impact. The usual sequence of one g/zero g/impact, without the possibility of a useful "coast" phase, as done in horizontal facilities, causes shifts in initial conditions for the test impact pulse which can affect the response to the impact. The significance of this depends on the dynamic characteristics of the system being tested, and these are seldom known with sufficient accuracy to enable the response to be corrected. In addition, earth's gravity opposes the final rebound of the test dummies into the seat back, so that an adequate test of seat back strength and support for the dummy cannot be obtained. The problems in Test 1, or with rear facing seats in Test 2, are not as difficult because the seat supports the dummy occupant prior to the free fall. However, the zero g condition which exists prior to impact allows the test dummy to "float" in the seat/restraint system, perhaps changing position and certainly changing the initial impact conditions. Again, use of an auxiliary break-away restraint system to correct these problems is difficult.
c. Test Fixtures. A test fixture is required to position the test article on the sled or drop carriage of the test facility and takes the place of the airplane's floor structure. It holds the attachment fittings or floor tracks for the seat, providing the floor and sidewall deformation needed for the test; it provides anchorage points, if necessary, for the restraint system ; it provides a floor or footrest for the test dummy; and it positions instrument panels, bulkheads, or a second row of seats, if required, for successful testing and otherwise simulates the airplane for the test. The test fixture is usually fabricated of heavy structural steel and need not simulate lightweight airplane design or construction. The details of the fixture depend upon the requirements of the test articles, but some capability for providing floor and sidewall deformation is needed.
(1) Purpose of Floor Deformation. The purpose of providing floor deformation for the tests is to demonstrate that the seat/restraint system remains attached to the airframe and performs properly even though the airplane and seat are severely deformed by the forces associated with the crash. Typical design deficiencies addressed by this test condition include, but are not limited to, the following:
(i) Concentrated loads may be imposed on floor tracks by seat attachment fittings which fit tightly or are clamped to the track and which do not have some form of lateral "roll" relief incorporated in their design. These fittings can concentrate the forces on one lip of the floor track and break the track or the fitting.
(ii) Similarly, loads can be concentrated on one edge of a floor track or fitting having an "I" or "bulb head" cross section and prematurely break the flange or the fitting.
(iii) Detents or pins which lock the seat to the floor track can become disengaged or the mechanism which is used to disengage the detents or pins can be actuated and release the seat as the seat deforms.
(iv) Seat assemblies which provide an energy absorbing system between a seat "bucket" and a seat frame may not perform properly for a pre-loaded seat frame attached to the floor or sidewall. Deformation of the seat frame may cause the energy absorbers to receive unanticipated loads or cause excessive friction in the guides between the seat bucket and seat frame to lock the energy absorber in place.
(v) Restraint system anchorages attached to the airframe may experience excessive displacement relative to the seat if the seat deforms during the test, and such displacement may inhibit proper performance of the seat/restraint system.
(2) Method of Floor Deformation. For the typical seat with four seat legs mounted in the airplane on two parallel tracks, the floor deformation test fixture may consist of two parallel beams, a "pitch beam" which pivots about a lateral (y) axis, and a "roll beam" which pivots about a longitudinal (x) axis. The beams can be made of any fairly rigid structural form, box, I-beam, channel, or other appropriate cross section. The pitch beam should be capable of rotating in the x-z plane up to + or - 10 degrees relative to the longitudinal (x) axis. The roll beam should be capable of + or - 10 degrees roll about its own axis. A means should be provided to fasten the beams in the deformed positions. The beams should have provision for installing floor track or other attachment fittings on their upper surface in a manner which does not alter the above-floor strength of the track or fitting. The track or other attachment fittings should be representative in abovefloor configuration and strength to that which would be used in the airplane.
Structural elements below the surface of the floor which are not part of the floor track or fitting need not be included in the installation. The seat should then be installed on the parallel beams so that the seat rear leg attachment point is near the pitch beam axis of rotation and the seat positioning pins or locks fastened in the same manner as would be used in the airplane, including the adjustment of "anti-rattle" mechanisms, if provided. The remainder of the test preparations would then be completed (dummy installation and positioning, instrumentation installation, adjustment and calibration, camera checks, etc.). The "floor deformation" would be induced as the final action before the test is accomplished.
The roll beam would be rotated 10 degrees and locked in place, and then the pitch beam would be rotated 10 degrees up and locked in place. It is also acceptable to rotate one track up 5 degrees and one track down for a total of 10 degrees of pitch deformation. The direction of rotation would be selected to produce the most 8
severe structural loading condition on the seat and floor track or fitting. If the seat is fairly flexible, it may be possible to rotate the beams by manual effort, perhaps using removable pry bars to gain mechanical advantage. However, rotation of the beams used for testing a stiff seat frame is likely to require greater effort than can be accomplished manually, and the use of removable hydraulic jacks or other devices may be necessary. If this condition is expected, provision should be made for appropriate loading points when designing the fixture. This condition is most likely to be encountered when rotating the pitch beam. Appropriate safety provisions should be made to avoid injury to operating personnel during the deformation process. If a facility anticipates testing a wide range of seat configurations, careful design of the test fixture so that it can be adjusted to fit the range of seat leg spacing enables one fixture assembly to be used for many tests.
(3) Alternative Configurations. The preceding discussion is for a floor-track system and describes the fixture and floor deformation procedure which would be used for a typical seat utilizing four seat legs and four attachments to the airplane floor. These test procedures are not intended to be restricted only to those seat configurations, but should be adapted to seats having other designs.
Special test fixtures may be necessary for those different configurations. The following methods, while not covering all possible seat designs, provide guidance for the more common alternatives:
(i) Airplane seats with three legs may have one central leg in front or back of the seat and one leg on each side of the seat. The central leg should be held in its undeformed position as deformation is applied to the sidelegs.
(ii) Seats which mount solely to a bulkhead need not be subject to the floor or sidewall deformation shown in figure 2 prior to the test. The test fixture may provide either a rigid bulkhead, or hold an actual bulkhead panel. If a rigid bulkhead installation is used, the test fixture should transfer loads to the seat/restraint system through components equivalent to the attachment fitting and surrounding bulkhead panel which exist in the actual installation.
(iii) Seats which are attached to both the floor and a bulkhead would be tested on a fixture which positions the bulkhead surface in a plane through the axis of rotation of the pitch beam. The bulkhead surface should be located perpendicular to the plane of the floor (the airplane floor surface, if one were present) in the undeformed conditions, or in a manner which duplicates or represents the intended installation. Either a rigid bulkhead simulation or an actual bulkhead panel may be used. If a rigid bulkhead simulation is used, the test fixture should transfer loads to the seat/restraint system through components equivalent to the attachment fitting which would exist in the actual installation.
The seats would be attached to the bulkhead and the floor in a manner representative of the airplane installation, and the floor would then be deformed as described in paragraph 4c(2).
(iv) Seats which are mounted between sidewalls or to the sidewall and floor of an airplane should be tested in a manner which simulates airplane fuselage cross-section deformation (e.g. from circular to flattened circular or ellipsoidal shape) during a crash. The test set-up including the brackets should 9
simulate the seat attachment at the same level above the fixture "floor" that would represent the installation above the airplane floor. A sidewall bracket should be located on the roll beam. Then, as the beams are rotated to produce the most conservative loading condition (sidewall rotates outward by 10 degrees), the combined angular and translational deformation simulates the deformation which may take place in a crash. The floor attachments should be pitched 10 degreees with respect to the undeformed floor position.
(v) Seats which are cantilevered from one sidewall without connection to other structure would not be subject to floor warpage or the standard floor deformation prescribed in § 23.562(b)(3). If sidewall deformation is likely, consideration should be given to moving the entire sidewall attachment plane, or the attachment points, in a manner to represent the sidewall deformation if this would generate a condition critical for seat attachment or seat/restraint system performance. Either a rigid sidewall simulation or an actual sidewall panel may be used. If a rigid sidewall simulation is used, the test fixture should transfer loads to the seat/restraint system through components equivalent to the attachment fitting and surrounding sidewall which would exist in the actual installation.
(vi) Multiple occupant seat assemblies may have more than two pairs of legs in some installations. These assemblies are usually of fairly constant cross section, so that adequate deformation can be generated if only the outer leg assemblies are subject to floor deformation. The inner leg pairs would be maintained in their normal, undeformed position for the dynamic tests.
(4) Other Fixture Applications. Test fixtures should provide a flat footrest for dummies used in tests of passenger seats and seats for crew members who are not provided with special footrests or foot operated airplane controls.
The surface of the footrest should be covered with carpet (or other appropriate material) and be at a position representative of the undeformed floor in the airplane installation. Test fixtures used for evaluating crew seats which are normally associated with special footrests or foot operated controls should simulate the position of those components. Test fixtures may also be required to provide guides or anchors for restraint systems or for holding instrument panels or bulkheads, if necessary, for the planned tests. If these provisions are required, the installation should represent the configuration of the airplane installation and be of adequate structural strength.
d. Instrumentation. Electronic and photographic instrumentation systems are used for the tests discussed in this AC. Electronic instrumentation is used to measure accelerations and forces required for verifying the test environment and for measuring most of the pass/fail criteria. Photographic instrumentation is used for documenting the overall results of the tests, confirming that the lap safety belt remained on the test dummy's pelvis and that the upper torso restraint straps remained on the test dummy's shoulder, and documenting that the seats did not deform as a result of the test in a manner which would impede rapid evacuation of the airplane by the occupants.
(1) Electronic Instrumentation. Electronic instrumentation should be accomplished in accordance with the Society of Automotive Engineers Recommended Practice SAE J211, Instrumentation for Impact Tests. Equivalent instrumentation is 10
also acceptable. In this SAE J211 practice, the data channel includes all of the instrumentation components from the transducer through the final data measurement, including connecting cables and any analytical procedures which alter the magnitude of frequency content of the data. Each dynamic data channel is assigned a nominal channel "class" which is equivalent to the high frequency limit for that channel, based on a constant output/input ratio vs. frequency response plot which begins at 0.1 Hz (+1/2 to -1/2 db) and extends to the high frequency limit (+1/2 to -1 db). Frequency response characteristics beyond this high frequency limit are also specified. When digitizing data, the sample rate should be at least five times the -3 db cutoff frequency of the pre-sample analog filters. Since most facilities set all pre-sample analog filters for Channel Class 1000, and since the -3 db cutoff frequency for Channel Class 1000 is 1650 Hz, the minimum digital sampling rate would be about 8000 samples per second. For the dynamic tests discussed in this AC, the dynamic data channels should comply with the following channel class characteristics:
(i) Sled or drop tower vehicle acceleration should be measured in accordance with the requirements of Channel Class 60, unless the acceleration is also integrated to obtain velocity or displacement, in which case it should be measured in accordance with Channel Class 180 requirements.
(ii) Belt restraint system loads should be measured in accordance with the requirements of Channel Class 60.
(iii) Anthropomorphic test dummy head accelerations used for calculating the Head Injury Criterion (HIC) should be measured in accordance with the requirements of Channel Class 1000.
(iv) Anthropomorphic test dummy pelvic/lumbar spinal column force should be measured in accordance with the requirements of Channel Class 60.
(v) The full-scale calibration range for each channel should provide sufficient dynamic range for the data being measured.
(vi) Digital conversion of analog data should provide sample resolution of not less than one percent of full-scale input.
(2) Photographic Instrumentation. Photographic instrumentation should be used to document the response of the anthropomorphic test dummies and the test specimens subjected to the dynamic test environment. Both high speed motion picture and still systems should be used.
(i) High speed motion picture cameras which provide data used to calculate displacement or velocity should operate at a nominal speed of 1000 pictures per second. Photoinstrumentation methods should not be used for measurement of acceleration. The locations of the cameras and of targets or targeted measuring points within the field of view should be measured and documented. Targets should be at least 1/100 of the field width covered by the camera and should be of contrasting colors or should contrast with their background. The center of the target should be easily discernible.
Rectilinearity of the image should be documented. If the image is not rectilinear, appropriate correction factors should be used in the data analysis process. A description of photographic calibration boards or scales within the camera field of view, the camera lens focal length, and the make and model of each camera and lens should be documented for each test. Appropriate digital or serial timing should be provided on the image media. A description of the timing signal, the offset of timing signal to the image and the means of correlating the time of the image with the time of electronic data should be provided. A rigorous, verified analytical procedure should be used for data analysis.
(ii) Cameras operating at a nominal rate of 200 pictures per second or greater can be used to document the response of anthropomorphic test dummies and test items if measurements are not required. For example, actions such as movement of the pelvic restraint system webbing (lap safety belt) off of the test dummy's pelvis or movement of upper torso restraint webbing off of the test dummy's shoulder can be observed by documentation cameras placed to obtain a "best view" of the anticipated event. These cameras should be provided with appropriate timing and a means of correlating the image with the time of electronic data.
(iii) Still image cameras can be used to document the pre-test installation and the post-test response of the anthropomorphic test dummies and the test items. At least four pictures should be obtained from different positions around the test items in pre-test and post-test conditions. For the post-test pictures, the upper torso of the test dummies may be rotated to their approximate upright seated position so that the condition of the restraint system may be better documented, but no other change to the post-test response of the test item or dummies should be made. The pictures should document that the seat remained attached at all points of attachment to the test fixture. Still pictures can also be used to document post-test yielding of the seat for the purpose of showing that it would allow the rapid evacuation of the airplane occupants. The test dummy occupants should be removed from the seat in preparation for still pictures used for that purpose. Targets or an appropriate target grid should be included in such pictures, and the views should be selected so that potential interference with the evacuation process can be determined.
e. Anthropomorphic Test Dummies. The tests discussed in this AC were developed using the anthropomorphic test dummies specified by the United States Code of Federal Regulations, Title 49, Part 572 Anthropomorphic Test Dummies, Subpart B - 50th Percentile Male, and modified to allow the measurement of lumbar loads. These "Part 572B" dummies have been shown to be reliable test devices which are capable of providing reproducible results in repeated testing. However, since anthropomorphic test dummy development is a continuing process, a provision was made for using "equivalent" test dummies. Dummy types should not be mixed when completing the tests discussed in this AC.
(1) Modification for Measuring Pelvis/Lumbar Column Load. Most readily available anthropomorphic test dummies have been developed for use in automobile testing. As a result, considerable effort has been spent in perfecting their response and ability to evaluate injury protection in forward, rearward, and sideward impacts. These characteristics are also important in testing systems for use in civil airplanes, but criteria should be added to account for injuries caused by impacts which have a component in the vertical direction or by upper torso 12