77-17-12: Wing Spar Chord Splice Joints

77-17-12 MARTIN: Amendment 39-3022. Applies to all Martin 404 Aircraft certificated in all categories. Compliance required as indicated. (a) For airplanes without wing spar chord splice joint fittings at wing station 187, accomplish the following: (1) Within the next three months or 500 hours in service, whichever occurs first, after the effective date of this AD, unless accomplished within five years or 10,000 hours in service preceding the effective date, remove the left and right outer wing panels and visually inspect the wing spar chord splice joints for corrosion at wing station 187. (2) Repeat the inspection specified in (a)(1) at intervals not to exceed 10,000 hours in service or five years, whichever occurs first, for left wings, and 12,000 hours in service or six years, whichever occurs first, for right wings. (b) For airplanes with wing splice fittings installed in accordance with STC SA328SO, accomplish the following without wing removal:(1) Visually inspect the left and right wing panels at wing station 187 for corrosion within the next 12 months or 2000 hours in service, whichever occurs first, after the effective date of this AD, unless accomplished within 48 months or 8000 hours in service preceding the effective date by (i) Stripping all sealant from the spar splice joints. (ii) Removing any two vertical large attachment bolts and the two end horizontal tension bolts from each "Hayes" fitting. (2) Perform a dye penetrant inspection or an FAA approved equivalent inspection for cracks at the same time as the corrosion inspection specified in (b)(1). (i) At the accessible areas of the spars and (ii) In the four bolt holes of each "Hayes" fitting as noted in (b)(1)(ii) (3) Perform the inspection in (b)(1)(ii) which requires removal of the horizontal bolts even though any two vertical large attachment bolts have been removed for bolt hole inspection within the past 48 months or 8000 hours in service. (4) Repeat the inspection specified in (b)(1) at intervals not to exceed 10,000 hours in service or five years, whichever occurs first. (5) Remove both wing outer panels; conduct a corrosion inspection of the wing structure and fittings, and a dye penetrant inspection for cracks on all affected parts at intervals not to exceed 20,000 hours in service or ten years, whichever occurs first, beyond the inspection in (b)(1). (c) Repair corroded parts before further flight in accordance with an FAA approved repair or replace cracked parts before further flight with serviceable or equivalent parts approved by the Chief, Engineering and Manufacturing Branch, FAA, Eastern Region. (d) Upon submission of substantiating data by an owner or operator through an FAA Maintenance Inspector, the Chief, Engineering and Manufacturing Branch, FAA, Eastern Region, may adjust the inspection interval specified in this AD. Amendment 39-3022 revokes AD 75-26-08. This amendment is effective August 30, 1977.