Federal Aviation Agency .- AC NO: AC 29-1 EFFECTIVE : 12/26/63 SUBJECT : APPROVAL BASIS FOR AUTUMATIC STABIL’ftION EQUIHENT (A=) 0 INSTALLATIONS IN WTORCRAFT 1 0 PURPOSE. This circular sets forth acceptable means, not the sole means, by which compliance may be shown with the flight requirements for ASE installations in accordance with the reference regulatioasin 2 below.
2 0 REFERENCE REGULATIONS.
8. CARh 6.10 and 7.14 Eligibility for tfrpe certificates.
b 0 CARk 6.601 and 7.60l, Rmctfonal and installational requiremetits.
. c. CA& 6 l 606 (b) and 7 l 606 [b), Hazards.
3 0 DISCUSSION.
a. Parts 6 and.7 rotorcraft afrworthiness regulations do not speak specifically to flight requirements for the installation of ASE equipment. The referenced regulations do, however, set forth objective standards for the installation of optional equipment such as the automatic stabilization equipment, etc. This type of equipment has been installed and approved on several helicopters in the past, and the criteria set forth in this document are essentially the same as those utilized in the determination of compliance for these past apprwals. -* b 0 Basically, the means of compliance contained hereinare~imilar to that required for autopilot installatLons, and provide. for . the equipment to: .
. (1) F’unction properly (reference 6.601 and 7.601). (2) Not create any unsafe conditions in no-1 operation .
(reference 6.10 and 7.10).
0 Not create any hazard in the event of malfunction ot 8 f,ailure (reference 6.606(b) and 7.606(b).
’ -0 . AC 29-l 12/26/63 4 0 ACCEP LE Pi.EANS OF COMPLUNCE, .
a0 An analysis of the automatic stabilization equipment system camponents and associated systems should be made to deternine to t extent a single failure will producehignals ia the ayetern wh%cb wil1 adversely affect the flight control syetem. Them l nals should be htroduced during flight test 8s required fn b eO To preclude hazardous condftions which may result from any failure or ma’lfunetioning of the automatic stabilkation equtpment, or its se by the h-an pilot, the folloti~ coadLti.on~ ehould ?M investigated by flight tests:
(I) A signal about any axis equivalent to the emulative effect of any single failure (or if multiple axis failure can rerult from the malfunction of any single component, combLned rignals from al.1 affected axes) should be induced into the automatic stabilization equfpment during all mmeuvers and flight regimes appropriate to its use. . -
(2) ff the equipment is to be approved without flight restrictions (operating at all times& such ma3functions should be demonstrated to be satisfactory during takeoff, climb, cruising, landing, maneuvering, and hovering.
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(3) Hf a flight restriction is provided, it should be determined as appropriate for the type and its operation. Appropriate operating Umitations should be specified and significant information regarding the restriction should be made available to the pilot in the dperating procedures section of the rotorcraft flight manual. A means shall be provided to engage L. and diseragage the equipment and a visual mmm rhould be prdvided to indicate when the equipment is operatltng,
(4) When corrective action is taken with appropriate time delay after the rotorcraft response-‘to the malfunction, neither the simulated fatlure nor the subsequent corrective action should create either hazardous loads or speeds, or dangerous attitude or flightpath deviations. .
(5) Recovery should be demonstrated with the use of normal controls
- QP by manual use of an emergency disconnect, tf such a device fu provfded, after the appropriate time delay.. The p&lot o .
srhould be able to return the rotorcraft to its aonaal -flight attitude under full manual control without exceeding the loads and speeds previously described and without engagfng in any dangerous manewers during recovery.
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AC 29-l CH 1 3/26/64
(6) The following time delays should be used and are considered appropriate for the various flight regimes and maneuvers:
(a) One to three seconds delay for cruising flight. (The time delay selected should be based upon the degree of stability provided and the amount of alertness required of the pilot. For example, three seconds are required for a fixed wing transport aircraft %n cruising flight).
- NOTE: If the improved stability and the rerultant higher degree of relaxation by the pilot has justified time delays greater than one-second minimum in cruise, then a reexamination is Iln order of the engine failure time s ‘delays used durfng the original type certification prior . i to the ASE installation. (CAR 6.121(e) and CM 7.121(e)). m
(b) One second delay for climbing flight.
( 1 C Zero second delay for takeoff, landing, hovering, and .
maneuvering flight.
(7) If any significant loss of altitude is experienced in any flight regime or maneuver, it should be provided as emergency operation information.
(8) The automatic stabilization equipment should be installed mch that lateral, directional, and longitudinal controllability (CAR 6.121) are not affected adversely; It should be demon- m strated that with a critical malfunctfon at critical airspeeds (such as Vne and maximum sideward flight) it is possible for the pilot to maintain complete control of the rotorcraft.
(9) The automatic stabilization equipment should be able to perform its dntended function throughout all maneuvers appropriate * to its type. All such maneuvers should be accomplished smoothly.
(10) If trim controls are provided in the automatic stabilization system, they should be’of such design and ao installed that any failure will not create a hazardous condition. If an inadvertent out-of-trim condition can be developed, its effect on the ASE or the rotorcraft should be lmrerttgated. ‘These .
trim controls should be such that when installed, the controls should operate in the plane and with the aense of motion * of the rotorcraft. Each control means should have the dlrec- - tion of motion plainly marked thereon or adjacent to the control.
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Yage 4 AIC 29-l 12/26/63 The automatic stabilization equtpment should be so installed that its operation will not be adversely affected by spurious signals from other sources, or 8s a result of nomal variations fn the automatic stabilization system power source, or feedback by other equipment operating fran the ame power source@ A positive means should be provided to Indicate to the pilot when the oPutomatfc stabfffzation equipment is ready for operation or when the gyroscop%c emonents are uncaged, unless it is impossfble.to engage the equtpment before it is ready for operation.
A visual means should be provided to Ladicate when the equfpmerit ‘i$ operative. If the design is such and the installation made such that it is possible to render a channel inoperative separately, then a visual means should be provided to indicate when each channel is operative.
The auto-tic stabilization equipment should be so installed and adjusted that the control.authority for each axis can be maintained wfthin tolerm'ce in normal operation. These tolerances should be establi.shed and Included on the aircraft specifications with the associated amount of control authority for each appropriate axis.
The following information should be provided in the rotorcraft flight manual :
(a) Any applicable operating limitations.
(b) The normal operatfng procedures.
(c) The kmergency operating procedures,fncluding a statement of altitude lost in any flight regime, if it is appropriat co Uthough the preceding material refers to automatic stabilization equipment which may be interpreted as stability about all axes, it is intended also that this gutdance material should be applicable to single axis stability augmeators, where appropriate.
d. Approval of automatfc stabLlitation equipment in accordance with this materiaLdoes not constitute approval oft he equQment or. the rotorcratt for instnment flight.
Flight Standards Service Par 4