APPENDIX 8 FUNCTIONAL AND RELIABILITY TESTS -§ 21.35(b)(2)
1. Explanation.
a. In order to satisfactorily accomplish the objectives concerning additional flight tests and the extent thereof, the Administrator deems it necessary that:
(1) A comprehensive and systematic check be made, in flight, of the operation of all components to determine whether they "function properly" (i.e., perform their intended function without introducing safety hazards).
(2) Sufficient FAA test experience, and supplementary experience gained from operators' route proving tests, should be obtained and evaluated to give reasonable assurance that the airplane is "reliable" (i.e., should continue to function properly in service).
NOTE: In order to obtain wider experience, manufacturers are encouraged to cooperate with airlines or other responsible operators in operating airplanes with provisional type certificates under service conditions.
(3) Appropriate corrective action be taken when the need therefor is determined under subparagraphs (1) and (2) of this paragraph.
2. Procedures . The principal FAA flight test pilot for the project will act as coordinator of all flight activities during the official program, and that pilot (or a designated alternate) will participate in all flights. Other FAA personnel will not board the functional and reliability (F & R) airplane(s) during these activities, particularly in regard to flight plans and procedures, unless authorized by the flight test pilot. The manufacturer's pilot should be in command of all flights, but FAA pilots will fly the airplane to determine compliance with § 21.35(b)(2). Other FAA personnel (e.g., representatives of other divisions and specialists) will participate in the flight tests, when deemed necessary, to accomplish the purpose of the tests.
a. Test Time. It is highly desirable that function and reliability test programs be administered uniformly so that the program and flight time for a given project would be approximately the same, regardless of which FAA Aircraft Certification Office (ACO) administered the project. This is difficult to achieve without establishing fixed arbitrary test times, which would obviously be contrary to the intent of § 21.35 (b)(2). The following procedure, which permits considerable flexibility, is therefore established as guidance for administering F & R test programs:
(1) For a turbine engine-powered airplane incorporating engines of a type not previously certifi cated, §
21.35(f)(1) requires an F & R test program of at least 300 hours. This 300 hour minimum may also be applied to a complex new airplane model (e.g., an airplane with an electronic flight control system (fly by wire)). Though some F & R test requirements can be completed concurrently with certification testing (if relevant design conformity can be shown), experience has indicated the desirability of obtaining at least 150 hours on a production configured airplane. For a previously certificated airplane, the F & R program requirement should be commensurate with the modifications or changes.
(2) When supplementary experience is not taken into account, and the airplane is conventional with regard to complexity and design features and does not incorporate engines that have not been previously certificated (including derivative engines), it has been found that function and reliability tests can be performed within 300 hours. This time may be reduced if credit is granted for certain types of component testing (see paragraph 2e(2)) and for supplementary experience (see paragraph 2a(3)(iii). However, it may be necessary to increase the 150-hour minimum F & R test requirement of § 21.35(f)(2) if difficulties are encountered or for unusual cases of complexity.
(3) When satisfactory supplementary experience is available and taken into account the following allowances should be used as a guide and applied with judgment in reducing the official flight test time. However, in any case, the official F & R test program should provide sufficient time to accomplish the objective of paragraph 1a(2) in accordance with the procedures described in paragraphs 2e(3) and (4).
(i) For Intensive Experience . When the allowance is based on the total time of any one airplane in airline crew training and similar intensive operations, two hours of such operation may be considered equivalent to one hour of official testing.
(ii) For Miscellaneous Experience . When the allowance is based on the total time of any one airplane, five hours of such experience may be considered equivalent to one hour of official testing.
(iii) Reduction for Supplementary Experience . Whenever a reduction of official test time is desired on the basis of supplementary experience, such experience should be adequately recorded and submitted to the responsible FAA aircraft certification office as described in paragraph 2f(2).
b. Test Airplane . To facilitate completion of the type certification procedure, one airplane, in production configuration or equivalent, should be used for the official functional and reliability tests while another airplane (or airplanes) is used for the routine-type tests. In this case, the test time on at least one airplane would be sufficient to accomplish the objective of paragraph 1a(2).
c. Modified Types . The procedure outlined in paragraph d., below, applies to new type designs. When a design employs components (parts) identical to those used in previous designs, credit may be given for the supplementary experience available for such components. When a design is modified (e.g., several versions of the same basic type with different engines, propellers, etc.), the modified features and components should be rechecked in accordance with paragraph 2e(6), below.
d. Test Program. The project engineers of the responsible FAA ACO will propose guidelines for developing an F & R test program at the preflight Type Board meeting (prior to commencement of FAA certification flight tests) and coordinate this with the airplane manufacturer. Near the conclusion of the type certification tests, the FAA certification engineers will again meet with the manufacturer to review the experience gained in those tests, review changes made in the design, consider any additional supplementary experience, and revise the proposed F & R test program accordingly. In application, there is generally considerable overlap of the certification and F & R test programs, thus making a definite transition point indiscernible.
e. Planning and Execution of Test Program . The following points should be considered:
(1) The test program should be sufficiently well planned to enable its execution in an efficient manner without overlooking important items. Documentation should focus on the test objective(s) but does not necessarily require the type of detail maintained for type certification testing. The FAA project engineers will review the design features and equipment (appliances) with respect to the general objective and prepare a list showing:
(i) Components and systems to be checked in accordance with the procedures described in paragraph 2e(4).
(ii) A brief description of the operations to be performed, where these are not obvious (referencing any necessary operating instructions).
(iii) Special checks or likely critical conditions.
(iv) Estimated flight time required.
(2) Allowance may be made for those functional tests whose requirements are covered by 14 CFR part 25 type certification tests. Allowance may also be made for qualification-type testing of new features and equipment; however, the flight test program should be planned to determine the adequacy of these tests and the accuracy of the simulated operating environment (e.g., to determine whether the actual environmental conditions such as temperature variation, etc., are covered by the test simulations) when these may be critical, and to determine whether the installation and connected systems are satisfactory. This does not imply that flight tests must be conducted under the most severe outside air temperatures likely to be encountered in service. It should normally be possible to determine the effects of extreme outside temperatures on local temperatures by extrapolation or by
suitable correction factors. The FAA project engineers will then make a consolidated estimate of the total flight time required, allowing for overlapping, and adjust this in accordance with the "Test Time" outlined in paragraph 2a.
(3) This program will be arranged to permit the principal FAA flight test pilot to become thoroughly familiar with the operational aspects of the airplane in its anticipated service environment.
(4) All components of the airplane should be intensively operated and studied under all operating conditions expected in service and obtainable within the time and geographical limitations of the tests. Intensive operation means repeated operation of components in various sequences and combinations likely to occur in service.
Particular attention should be given to potential sources of crew error, excessive crew workload or coordination, and the procedures that would be required in the event of malfunction of any component. The testing should also include an evaluation of operations with various Minimum Equipment List (MEL) items declared/simulated inoperative. This intensive type of testing should be conducted in all cases, but the length of time for which it is continued will depend upon the supplementary experience available for the particular type, as outlined in paragraph 2a, "Test Time."
(5) Ground inspections should be made at appropriate intervals during the test program to determine whether there are any failures or incipient failures in any of the components that might be a hazard to safe flight.
The normal maintenance procedures should be employed during the F&R Program and carefully documented for review.
(6) When design changes are made during the course of the test, or when the official test airplane differs from those on which supplementary experience is obtained, the modified items will be rechecked in accordance with the above procedures. Every effort should be made to include such items in the program in such a way as to avoid unduly extending the overall test time. To this end, the Administrator may accept, in lieu of additional flight tests:
(i) special tests of the original and revised components in which the conditions causing failure are intensified.
(ii) ground qualification tests of differing components when the test methods have been validated as being representative of actual flight conditions.
f. Reports and Records .
(1) A log should be kept of all flights, and accurate and complete records kept of the inspections made of all defects, difficulties, and unusual characteristics and sources of crew error discovered during the tests, and of the recommendations made and action(s) taken. Items for which design changes may be required will be reported to the manufacturer and the appropriate FAA ACO.
(2) If supplementary experi ence is to be taken into account, similar records of such experience should be kept and submitted to the responsible FAA ACO, together with a list of the differences between the airplane on which the experience was obtained and the official test airplane. When supplementary experience is obtained on a large fleet of airplanes (for example, military operations) of the same or a comparable type (see paragraph 2e(6)), these records may consist of statistical summaries in lieu of complete records for each individual airplane.
(3) At the conclusion of the official tests, a summary report should be prepared by the participating pilots, engineering specialists, and manufacturing inspectors and made a part of the Type Inspection Report.