Appendix 6 AC 20-59 CH 1 Page 4 8/24/72 * 3. EMPENNAGE.
a. Rudder Support Channels.
(1) Structural failure in the area of the rudder support channels caused by compression and tension loads of the rudder torque tube is a possibility.
(2) Refer to Service Bulletin 340-147 dated 25 April 1955.
b. Vertical Stabilizer Front Spar Rails.
(1) Cracks have been found in the radius where the leading edge attaches.
(2) This problem found only on Navy (R4Y) aircraft. No service data published.
c. Rudder Stop Angle Failures.
(1) Failures of the rudder stop angles have occurred.
(2) Refer to Service Airgram 174 dated 4 May 1956.
4. WING.
a. Front Spar Lower Rail.
(1) Cracks have been found in the front spar lower rail on aircraft in service.
(2) Refer to Service Engineering Report 057-0/67-340-64/440-64 dated 31 May 1967.
b. Splice Plate - Station 8.
(1) During the Model 340 wing fatigue test, a crack developed at the Station 8 splice plate area after approximately 270,000 cycles.
(2) Refer to Service Engineering Report 6820-340-47B/440-47B dated 15 January 1963 and Service Engineering Report 15-4-340-18B/440-22B dated 3 February 1965.
Main Landing Gear Beam.
(1) Operators have reported cracks in the main landing gear beam web upper flange radius.
(2) Refer to Service Bulletin No. 57-3 dated 17 April 1970. * Par 3
AC 20-59 CH 1 Appendix 6 8/24/72 Page 5 * d. Main Landing Gear Drag Link Fittings.
(1) Operators have been finding cracks in the main landing gear drag link fittings attached to the front spar.
(2) Refer to Service Bulletin No. 57-5A dated 20 July 1970.
e. Main Landing Gear Trunnion Fitting.
(1) Cracks have been found in the main landing gear trunnion fittings.
(2) Refer to Service Bulletin No. 57-4 dated 25 May 1970.
f. Lower Surface Skin.
(1) One operator reported a crack in the wing lower skin and horizontal rail of the left wing front spar lower rail at Wing Station 6.75.
(2) Refer to Service Bulletin A57-6 dated 1 June 1970.
g. Lower Surface Stringers.
(1) Stringers No's. 7 and 9 have been found cracked at the ends in the radius of the skin flange adjacent to the wing access doors at stations 9, 10, 12, 13, 15 and 16.
(2) Refer to Service Bulletin 340-148 dated 31 December 1954.
h. Station O Bulkhead Installation.
(1) Cracks have been experienced at the corner radius of spotfacing on splice forgings at wing station O.
(2) Refer to Service Bulletin 340-94 dated 12 May 1953.
1. Trailing Edge.
(1) Trailing edge skins are found deformed in service.
(2) Refer to Service Bulletin 340-104.
(3) Trailing edge ribs are being worn by the aileron cable.
(4) Refer to Service Engineering Report 6-2-340-2/440-4 dated 15 November 1957. * Par 4
Appendix 6 AC 20-59 CH 1 Page 6 8/24/72 * j. Lower Surface Skin Station 9.5.
(1) While investigating a fuel leak one operator found the doubler at the left hand access door at wing station 9.5 cracked.
(2) Refer to Alert Service Bulletin A57-2 dated 13 March 1968.
k. Nacelle Lower Outboard Longerons.
(1) Cracks have been reported in the nacelle lower outboard longerons.
(2) Refer to Service Engineering Report 6-2-340-1/440-3 dated 6 December 1957.
1. Wing Skin in Area of Main Landing Gear Drag Link Fittings.
(1) Cracks have been found in the wing skin in the area of the main landing gear drag link fittings.
(2) Refer to Service Bulletin No. A57-6 dated 1 June 1970.
m. Nacelle Drag Angles.
(1) Cracks have been discovered in the area where the nacelle drag angle crosses the front spar.
(2) Refer to Newsletter Review page B-2.
n. Inboard Flap Support Structure.
(1) Cracks have been experienced in the flap support structure.
(2) Refer to Service Bulletin 340-221 dated 25 October 1957.
Par 4 87412