64-04-03 CHAMPION: Amdt. 683 Part 507 Federal Register February 8, 1964. Applies to All Models 7GCB, 7GCBA, 7KC and All Models 7GC, 7GCA and 7HC Series Aircraft Using the 4-1099 Airscoop Box with Elliptical Fram Air Filter.
Compliance required within 50 hours' time in service after the effective date of this AD unless already accomplished.
As a result of several cases of engine power loss due to the carburetor alternate air door being sucked into the engine, make the spring loaded alternate air door inoperative by one of the following:
(a) Locking the door in the closed position by installing a 0.040 x 1/2 x 4 1/2 5052- H34 aluminum strap or equivalent across the door and attach with two AN 515-8-6 screws and AN 365-832 nuts; or
(b) Removing the entire door assembly and covering the opening with a 0.040 x 4 x 4 5052-H34 aluminum patch or equivalent. Attach the patch with eight AN 470AD3-4 rivets evenly spaced.
(Champion Service Letter No. 59 covers the same subject.)
This directive effective March 9, 1964.