51-25-01 CESSNA: Applies to All Model T-50 Aircraft.
Compliance required prior to February 1, 1952, and as noted.
To preclude trapping water in the horizontal stabilizer forward of the rear spar which may result in glue line deterioration between laminations, compliance with the following items is necessary:
1. Grommets must be installed sufficiently near the forward face of the rear spar and outboard edge of all ribs to drain any water which may be trapped. All grommets not so located must be relocated accordingly. Marine-type grommets are recommended at least at the inboard ribs.
2. All grommets which are plugged must be opened preferably with a sharp-edged tool and/or relocated in accordance with item 1 above. Special care should be taken to make sure that foreign matter is not allowed to build up on the inside around the drain openings.
3. Where grommets are mislocated, plugged, clogged with dirt or extraneous matter or have not been installed, the rear spar must be inspected for deterioration by cutting small triangular openings at the ribs adjacent to the fuselage and at alternate ribs outboard. If lamination separation is disclosed, a new spar should be installed or the stabilizer replaced with one having drainage provisions in accordance with item 1 above.
Upon accomplishment of the above, the grommet openings should be inspected at each 100 hours thereafter to maintain proper drainage. This inspection should include insertion of a bent or curved tool through the grommet openings to ascertain that dirt or other extraneous matter has not built up around the opening to restrict drainage. Where grommets are found clogged, inspection and compliance in accordance with item 3 above should be repeated.
This supersedes AD 44-26-01.