76-20-07 BELLANCA: Amendment 39-2738. Applies to Bellanca CH, CH-300 Pacemaker, 300-W Pacemaker, CH-400 Skyrocket, E Pacemaker, F. Skyrocket, 14-9, 14-9L, 14- 12F-3, 14-13, 14-13-2, 14-3-3, 14-13-3W, 31-42 Pacemaker Aircraft, certificated in all categories.
To prevent failure of forward or aft wing spars due to wood decay caused by water collecting in the wing, accomplish the following: Prior to the next flight after receipt of this AD unless already accomplished, and at each annual inspection thereafter, perform the following or an approved equivalent inspection:
(a) Using a blunt tool (e.g. screwdriver handle) tap along the entire length of the upper and lower skin directly over the front and rear spars starting inboard of the root rib. A decayed area will emit a sound that has a discernible difference in quality in comparison to an undecayed section. Fabric covered wings can be inspected by depressing the fabric over the spar prior to tapping. A suspected area mustbe inspected visually through available skin access holes, or cut outs in the skin. The front face of the rear spar and the front spar must also be checked by inserting an awl through the drain holes on the lower surface of the wing and tapping.
(b) Using a light and mirror, inspect the interior of the wings for moisture, water stains, pooled dust or dirt which may indicate previously collected water, wood discoloration, woodchecks, delamination of surfaces and corrosion of metallic surfaces. The inspection will include among other areas:
1. Inboard of root rib including the ends of front and rear spar and spar attachment and the inside surface of top and bottom skin and root rib.
2. Forward face of front spar visible through gap between fuselage and lower wing surface.
3. Forward face of rear spar to root rib, visible through gap between fuselage and lower wing surface.
4. Aft face of rear spar, visible through lightening holes or cut-outs after flaps are removed. For airplanes not equipped with flaps a skin cut-out on the bottom wing may be used.
5. Flap stops for airplanes so equipped.
6. Forward face of front spar in the vicinity of landing light for airplanes so equipped.
7. The plywood wing skin interior for airplanes so equipped.
8. Interior of wing at trailing edge where fabric terminates including the area around the flaps for airplanes so equipped.
9. Inspect for restriction in all drain holes in wing bottom surface.
10. Inspect the seal (e.g. fabric fillet, channel rubber with compatible sealant etc.) at the intersection of the fuselage and top wing skin leading edge fairing.
11. Inspect for serviceability of the seal (e.g. doped fabric fillet, silicone rubber sealant, etc.) between the fuel tank scupper and wing skin.
12. The spar butt ends.
(c) On the exterior surfaces of the wing, inspect for any damage that may allow water entry such as cracks or breaks in the paint,bubbles, discoloration, boils, soft spots or other evidence of fabric deterioration or fabric delamination from wood skin. Include in the inspection the wing root area, top and bottom surfaces of front and rear spars inboard of landing gear, wing walk area for airplanes so equipped and the top and bottom of the fuel tank area.
(d) If any defects set forth in paragraph (b) and (c) are detected, repairs must be accomplished in accordance with FAA-approved standard practice AC 43-13-1A or an equivalent repair approved by the Chief, Engineering and Manufacturing Branch, FAA, Eastern Region, prior to further flight, except that the airplane may be flown in accordance with FAR 21.197 to a base where the repair can be performed.
(e) All skins that are cut out in accordance with paragraph (a) must be repaired in accordance with paragraph (d).
This amendment is effective October 8, 1976 and was effective upon receipt for all recipients of the airmail directive of July 14, 1976.