46-36-03 PIPER: (Was Mandatory Note 2 of AD-780-3.) Applies Only to PA-12 Aircraft Serial Numbers 12-1 to 12-285, Inclusive.
Compliance required not later than next periodic inspection.
To prevent possible failure of the tailpipe and cracking of the muffler, install the additional brace tube, Piper P/N 10860 and new clamp, P/N 80002-28. The new brace will form, together with the original brace, a "V" instead of a single leg. A careful inspection of the muffler should be made and if any cracks are present, a new muffler should be installed.
(Piper Service Bulletin No. 92 dated August 7, 1946, covers this same subject.)