AD 93-08-08

93-08-08 DE HAVILLAND, INC.: Amendment 39-8555. Docket 92-NM-144-AD.

Applicability: Model DHC-8 series airplanes equipped with microwave landing system (MLS) provisions, as listed in de Havilland Service Bulletin S.B. 8-34-60, Revision 'C,' dated November 1, 1991; certificated in any category.

Compliance: Required as indicated, unless accomplished previously.

To prevent the airplane from landing short of the runway, accomplish the following:

(a) Prior to installation of an MLS, or within 45 days after the effective date of this AD, whichever occurs later, perform a general visual inspection to determine whether the vertical deviation wiring has been properly installed and/or connected to link the MLS with the ground proximity warning system (GPWS), in accordance with de Havilland Service Bulletin S.B. 8-34-60, Revision 'C,' dated November 1, 1991.

(1) If any vertical deviation wiring has been found that has not been properly installed and/or connected to link the MLS with the GPWS, prior to further flight, correct the wiring and perform a functional test of the system in accordance with the service bulletin.

(2) If vertical deviation wiring has been found that has been properly installed and/or connected to link the MLS with the GPWS, no further action is necessary.

(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: 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 FAR 21.197 and 21.199 to operate the airplane to a location where the requirements of this AD can be accomplished.

(d) The inspection, wiring correction, and functional test shall be done in accordance with de Havilland Service Bulletin S.B. 8-34-60, Revision 'C,' dated November 1, 1991. This incorporation by reference was approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR Part 51. Copies may be obtained from de Havilland, Inc., 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, 181 South Franklin Avenue, Room 202, Valley Stream, New York 11581; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC.

(e) This amendment becomes effective on May 26, 1993.