Piper Service Bulletin No. 61
Applicability: Piper J-3, J-4, J-5, L-4 and L-4A
Issue Date: February 20, 1946
Subject: Aging of Protective Finish on Wood Wing Spars
Summary: A noticeable aging of the spar finish occurs in listed airplane models that are continually exposed to adverse atmospheric conditions.
Open PDF: PIP_SB61.pdf