AD 97-20-10 Airworthiness Directives; de Havilland Model DHC-8-100, -200, and -300 Series Airplanes

Models named: DHC-8-100, -200, -300 series. Read the applicability below — it usually turns on serial or part numbers too.

Model DHC-8-100, -200, and -300 series airplanes; serial numbers 3 through 472 inclusive; certificated in any category. Note 1: This AD applies to each airplane identified in the preceding applicability provision, regardless of whether it has been modified, altered, or repaired in the area subject to the requirements of this AD. For airplanes 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 as indicated, unless accomplished previously. To prevent simultaneous power loss to both attitude and heading reference systems (AHRS), which could result in reduced controllability of the airplane, accomplish the following: (a) Within 400 hours time-in-service after November 3, 1997 (the effective date of AD 97-20-10, amendment 39-10147), modify the AHRS's, in accordance with Bombardier Alert Service Bulletin S.B. A8-34-117, Revision `C', dated February 14, 1997. (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, New York Aircraft Certification Office (ACO), FAA, Engine and Propeller Directorate. Operators shall submit their requests through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, New York ACO. Note 2: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the New York ACO. (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 airplane to a location where the requirements of this AD can be accomplished. (d) The modification shall be done in accordance with Bombardier Alert Service Bulletin S.B. A8-34-117, Revision `C', dated February 14, 1997. This incorporation by reference was approved previously by the Director of the Federal Register as of November 3, 1997 (62 FR 50861, September 29, 1997). Copies may be obtained from Bombardier, Inc., Bombardier Regional Aircraft Division, Garratt Boulevard, Downsview, Ontario M3K 1Y5, Canada. Copies may be inspected at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the FAA, Engine and Propeller Directorate, New York Aircraft Certification Office, 10 Fifth Street, Third Floor, Valley Stream, New York; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC. Note 3: The subject of this AD is addressed in Canadian airworthiness directive CF-97-01R2, dated August 13, 1997. (e) This amendment becomes effective on September 11, 1998. Issued in Renton, Washington, on July 31, 1998. Darrell M. Pederson, Acting Manager, Transport Airplane Directorate, Aircraft Certification Service. [FR Doc. 98-21097 Filed 8-6-98; 8:45 am] BILLING CODE 4910-13-P