86-25-03 THE DEHAVILLAND AIRCRAFT COMPANY OF CANADA, A DIVISION OF BOEING OF CANADA, LTD.: Amendment 39-5478. Applies to all Model DHC-7 and DHC-8 series airplanes, certificated in any category. Compliance is required as indicated, unless already accomplished.
To prevent the elevator trim-tab from becoming inoperable due to accumulated water freezing in the trim-tab jack-screw housing, accomplish the following, unless already accomplished.
A. For Model DHC-7 airplanes, within three months after the effective date of this AD, incorporate de Havilland Modification Number 7/2489 to provide a drain hole in the elevator trim-tab jack-screw housing in accordance with the "Accomplishment Instructions" contained in de Havilland Service Bulletin No. 7-27-76, dated January 17, 1986.
B. For Model DHC-8 airplanes, within three months after the effective date of this AD, incorporate de Havilland Modification Number 8/0415 to provide a drain hole in the elevator trim-tab jack-screw housing in accordance with the "Accomplishment Instructions" contained in de Havilland Service Bulletin No. 8-27-15, dated January 17, 1986.
C. An alternate means of compliance or adjustment of the compliance time, which provides an acceptable level of safety may be used when approved by the Manager, New York Aircraft Certification Office, FAA, New England Region.
All persons affected by this directive who have not already received the appropriate service documents from the manufacturer may obtain upon request to de Havilland Aircraft Company of Canada, a Division of Boeing of Canada Ltd., Garratt Boulevard, Downsview, Ontario M3K 1Y5, Canada. These documents may be examined at the FAA, Northwest Mountain Region, 17900 Pacific Highway South, Seattle, Washington, or FAA, New England Region, New York Aircraft Certification Office, 181 South Franklin Avenue, Room 202, Valley Stream, New York.
This amendment becomes effective January 12, 1987.