88-04-10 DEHAVILLAND AIRCRAFT COMPANY OF CANADA, A DIVISION OF BOEING OF CANADA, LTD.: Amendment 39-5855. Applies to Model DHC-7 series airplanes, equipped with Modification No. 7/2414, certificated in any category. Compliance required as indicated, unless previously accomplished.
To preclude the possibility of heat shield separation resulting from the failure of aluminum alloy washers, accomplish the following:
A. Within 60 days or 500 flight hours, whichever occurs first after the effective date of this AD, replace aluminum alloy washers with stainless steel washers, in accordance with the Accomplishment Instructions of de Havilland DHC-7 Service Bulletin No. 7-57-29, dated August 1, 1986.
B. An alternate means of compliance or adjustment of the compliance time, which provides an acceptable level of safety and which has the concurrence of an FAA Principal Maintenance Inspector, may be used when approved by the Manager, New York Aircraft Certification Office, FAA, New England Region.
C. Special flight permits may be issued in accordance with FAR 21.197 and 21.199 to operate airplanes to a base in order to comply with the requirements of this AD.
All persons affected by this directive who have not already received the appropriate service documents from the manufacturer may obtain copies upon request to The 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 April 5, 1988.