90-15-01: Tail Rotor Blade Assemblies

90-15-01 ROGERSON HILLER CORPORATION (HILLER, FAIRCHILD HILLER): Amendment 39-6879. Docket No. 90-ASW-39. Final Rule of priority letter AD. Applicability: All Model UH-12E, UH-12E-L, UH-12L, and UH-12L4 series helicopters, certificated in any category. Compliance: Required prior to further flight, unless already accomplished. To prevent failure of a tail rotor blade assembly, which could result in loss of controllability of the helicopter, accomplish the following: (a) Determine the part number and serial number of the tail rotor blade assemblies installed on the helicopter. The serial number is located on a raised rectangular boss on the barrel section of the blade root fitting. (b) If any tail rotor blade assembly installed is P/N 55073 and is identified with any of the serial numbers listed below, regardless of the hours' time in service, remove and replace the blade assembly with an airworthy part before further flight: Serial Numbers: 3028 3089 9506 9584 9607 10245 10516 10917 13278 14715 14898 15073 15285 15978 16114 20918 NOTE: Any unairworthy blade assemblies found as a result of this AD should be permanently marked as unairworthy. (c) If any of the tail rotor blade assemblies listed in paragraph (b) are found, report the helicopter registration number, serial number, and tail rotor blade assembly serial number to the Manager, Seattle Aircraft Certification Office (ACO), FAA, Northwest Mountain Region, Transport Airplane Directorate, within 10 days of the inspection required by paragraph (a) of this AD. (d) Special flight permits may be issued in accordance with FAR 21.197 and 21.199 to operate helicopters to a base in order to comply with the requirements of this AD. (e) Record compliance with paragraph (b) in the AD compliance record and in the maintenance record of the helicopter log book. This record must include the serial number of any deficient blade assembly foundduring compliance with this AD. (f) An alternate means of compliance or adjustment of the compliance time, which provides an equivalent level of safety, may be used when approved by the Manager, Seattle ACO, FAA, Transport Airplane Directorate, 1601 Lind Avenue SW., Renton, Washington. Note: The request should be submitted directly to the Manager, Seattle ACO, and a copy sent to the cognizant FAA Principal Inspector (PI). The PI will then forward comments or concurrence to the Seattle ACO. This amendment (39-6879, AD 90-15-01) becomes effective on March 7, 1991, as to all persons, except those persons to whom it was made immediately effective by Priority Letter AD 90-15-01, issued on July 11, 1990, which contained this amendment.