AD 99-07-17 Airworthiness Directives; Robinson Helicopter Company Model R22 Helicopters

Makes named: robinson. Models named: R22. Read the applicability below — it usually turns on serial or part numbers too.

Model R22 helicopters, serial numbers (S/N) 0002 through 2862, with sprag clutch, part number (P/N) A188-2, S/N's 3708 through 3757, 3808 through 3893, and 3908 through 4207, installed, certificated in any category. Note 1: This AD applies to each helicopter identified in the preceding applicability provision, regardless of whether it has been otherwise modified, altered, or repaired in the area subject to the requirements of this AD. For helicopters that have been modified, altered, or repaired so that the performance of the requirements of this AD is affected, the owner/operator must request approval for an alternative method of compliance in accordance with paragraph (b) of this AD. The request should include an assessment of the effect of the modification, alteration, or repair on the unsafe condition addressed by this AD; and, if the unsafe condition has not been eliminated, the request should include specific proposed actions to address it.

Required before further flight, unless accomplished previously. To alert pilots of the potential for the sprag clutch failing to overrun during autorotation due to failure of the sprags within the sprag clutch assembly, and loss of main rotor revolutions-per- minute, accomplish the following: (a) Insert either the Special Pilot Caution, revised March 22, 1999, which is contained in Robinson Helicopter Company R22 Service Bulletin SB-85, dated March 22, 1999, or the following Special Pilot Caution paragraphs, into the Normal Procedures section of the Rotorcraft Flight Manual, between pages P.4-8 and P.4-9: ------------------------------------------------------------------------ ------------------------------------------------------------------------- SPECIAL PILOT CAUTION Some sprags in overrunning clutches have been found cracked in service. A broken sprag could conceivably prevent the clutch from overrunning when entering autorotation. Until the clutch in this aircraft has been replaced, do not enter practice autorotations by rapidly closing or ``chopping'' the throttle. ``Chopping'' the throttle could result in a sudden loss of rotor RPM if the clutch failed to disengage. Enter autorotation by first lowering collective and then rolling off just enough throttle to produce a small visible split between the rotor and engine tachometer needles. If the clutch fails to disengage, immediately complete a power recovery. Perform hovering autos only after checking the function of the overrunning sprag clutch prior to lift-off, then smoothly rolling off the throttle from a low hover with the skids no more than two feet above the ground. Be sure to perform the sprag clutch check (split tach needles) before every flight, not just the first flight of the day. ------------------------------------------------------------------------ [[Page 17968]] (b) An alternative method of compliance or adjustment of the compliance time that provides an acceptable level of safety may be used if approved by the Manager, Los Angeles Aircraft Certification Office, FAA. Operators shall submit their requests through an FAA Principal Maintenance Inspector, who may concur or comment and then send it to the Manager, Los Angeles Aircraft Certification Office. Note 2: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Los Angeles Aircraft Certification Office. (c) Special flight permits may be issued in accordance with sections 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR 21.197 and 21.199) to operate the helicopter to a location where the requirements of this AD can be accomplished. (d) This amendment becomes effective on April 28, 1999 to all persons except those persons to whom it was made immediately effective by Priority Letter AD 99-07-17, issued March 26, 1999, which contained the requirements of this amendment. Issued in Fort Worth, Texas, on April 5, 1999. Eric Bries, Acting Manager, Rotorcraft Directorate, Aircraft Certification Service. [FR Doc. 99-9131 Filed 4-12-99; 8:45 am] BILLING CODE 4910-13-U