AD 86-07-08 ACTIVE

86-07-08 DEHAVILLAND: Amendment 39-5279. Applies to all Model DHC-7 series airplanes, certificated in any category. Compliance is required as indicated, unless already accomplished.

To ensure observation of wet starts, detection of heat-damaged wing upper surface structure behind the engine, and protection against wet starts of the engine resulting in external combustion of fuel, accomplish the following:

A. Except as provided in paragraph C., below, within the next 25 hours time-in- service after the effective date of this AD, insert a copy of this AD following Page 2-2-4B of the DHC-7 Airplane Flight Manual (AFM). After every aborted engine start in conjunction with either flight or other operations, follow AFM limitations and applicable procedures for starter cranking cycles, proper fuel draining, and dry motoring/clearing of the engine. An appropriately stationed observer must witness the subsequent starting attempt to determine whether external flames from the exhaust stacks and any burning of residual fuel on wing surfaces occurs.

1. If no external flame or external flame lasting for less than 5 seconds is observed, the airplane may be dispatched.

2. If external flame lasting 5 seconds or more is observed, a visual inspection of the affected wing area must be performed before further flight, in accordance with the Accomplishment Instructions, Paragraph 1, of DeHavilland Service Bulletin No. 7-57-25, Revision B, dated November 22, 1985.

a. If distortion or buckling of the skin is evident during the visual inspection, perform an internal conductivity survey of the affected area, and repair, as necessary, before further flight, in accordance with the Accomplishment Instructions of DeHavilland Service Bulletin No. 7-57-25, Revision B, dated November 22, 1985. Details of any damage discovered and data obtained from conductivity surveys must be transmitted to DeHavilland Aircraft of Canada, Ltd., immediately for processing.b. If blistering or charring of the paint due to engine exhaust heat is evident during the visual inspection, before further flight, perform an external conductivity survey and, as necessary, an internal conductivity survey, and make repairs, as necessary, in accordance with the Accomplishment Instructions of DeHavilland Service Bulletin No. 7-57-25, Revision B, dated November 22, 1985. Details of any damage discovered and data obtained from conductivity surveys must be transmitted to DeHavilland Aircraft of Canada, Ltd., immediately for processing.

c. If no visible damage (i.e., no blistering or charring of paint or buckling of the wing skin) is apparent, within 100 flight hours perform an external conductivity survey and, as necessary, an internal conductivity survey, and make repairs, as necessary, of the affected area in accordance with the Accomplishment Instructions of DeHavilland Service Bulletin No. 7-57-25, Revision B, dated November 22, 1985. Details of any damage discovered and data obtained from conductivity surveys must be transmitted to DeHavilland Aircraft of Canada, Ltd., immediately for processing.

B. Except as provided in paragraph C., below, within the next 25 hours time-in- service after the effective date of this AD, visually inspect the upper wing skin behind each engine nacelle in accordance with the Accomplishment Instructions, Paragraph 1, of DeHavilland Service Bulletin No. 7-57-25, Revision B, dated November 22, 1985.

1. If distortion or buckling of the skin is evident during the visual inspection, repairs must be effected before further flight. In order to determine the extent of repairs, perform an internal conductivity survey of the affected area in accordance with the Accomplishment Instructions of DeHavilland Service Bulletin No. 7-57-25, Revision B, dated November 22, 1985. Details of any damage discovered and data obtained from conductivity surveys must be transmitted to DeHavilland Aircraft of Canada, Ltd., immediately for processing.

2. If blistering or charring of the paint due to engine exhaust heat is evident during the visual inspection, before further flight, perform an external conductivity survey and, as necessary, an internal conductivity survey, and make repair, as necessary, of the affected area in accordance with the Accomplishment Instructions of DeHavilland Service Bulletin No. 7-57-25, Revision B, dated November 22, 1985. Details of any damage discovered and data obtained from conductivity surveys must be transmitted to DeHavilland Aircraft of Canada, Ltd., immediately for processing.

C. Accomplishment of DeHavilland Modification No. 7/2414 - "Wing - Upper Skin Structure - Special Inspection and Installation of Heat Shields," described in DeHavilland Service Bulletin No. 7-57-25 constitutes terminating action for the visual inspection and conductivity surveys required by paragraphs A. and B., above. When that modification has been accomplished, this AD may then be removed from the Airplane Flight Manual.

1. Prior to installation of Modification No. 7/2414, the following must be accomplished:

a. Perform an external conductivity survey and, as necessary, an internal conductivity survey, and make repairs, as necessary before further flight, of the upper wing skin behind each engine nacelle, in accordance with the Accomplishment Instructions of DeHavilland Service Bulletin No. 7-57-25, Revision B, dated November 22, 1985. Details of any damage discovered and data obtained from conductivity surveys must be transmitted to DeHavilland Aircraft of Canada, Ltd., immediately for processing.

b. For airplanes, serial numbers 1 through 27, Modification Nos. 7/2377 and 7/2378 - "Fuel Tank Access Panel Replacement," described in DeHavilland Service Bulletin No. 7-57-17 (originally issued October 12, 1983), must be accomplished.

D. Alternate means of compliance which provide an acceptable level of safety may be used when approved bythe Manager, New York Aircraft Certification Office, FAA, New England Region.

E. Special flight permits may be issued in accordance with FAR 21.197 and 21.199 to operate airplanes to a base for the accomplishment of inspections and/or modifications required by 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 DeHavilland Aircraft of Canada, Ltd., 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 22, 1986.