58-23-03 MOONEY: Applies to Model M-20 Aircraft Serial Numbers 1002 Through 1051.
Compliance required as soon as practicable but not later than December 15, 1958.
Several failures of the aileron counterbalance buttweld at the aileron spar have occurred. The affected airplanes do not have a 3/8 inch O.D. x 0.028 inch x 3 inch steel reinforcing brace installed.
It must be determined whether this brace has been incorporated. If not, the following inspection and repair must be accomplished:
1. Remove the paint from the subject welded joint and inspect for cracks.
2. Reweld the joint if cracks are present.
3. Install the 3/8 inch O.D. x 0.028 inch x 3 inch 4130 steel tubular brace (trimmed to fit).
(Mooney Aircraft, Inc. Service Letter 20-7 Revision B covers this same subject.)