AD 63-17-03

63-17-03 LOCKHEED: Amdt. 599 Part 507 Federal Register August 10, 1963. Applies to All Models 188A and 188C Series Aircraft Except Those Which Have Been Repaired in Accordance With Lockheed Service Bulletin 88/SB-579 or an Equivalent Approved By the Chief, Engineering and Manufacturing Branch, FAA Western Region.

Compliance required as indicated.

As a result of fatigue cracking in the horizontal stabilizer spar web at fuselage Station 1167.7, the following shall be accomplished:

(a) Within the next 210 hours' time in service after the effective date of this AD, inspect the horizontal stabilizer spar web at fuselage Station 1167.7, stabilizer Station 29, in the 0.62-inch radius near the lower cap and repair as necessary in accordance with the following:

(1) Clean the radius area and inspect for cracks using a dye-penetrant method or FAA approved equivalent. If a cleaner other than a mild soap solution is used, complete removal of the cleaning agent is required.(2) Any webs with cracks of 3/4 inch or less shall be stop drilled before further flight with a 3/8-inch diameter flat bottom drill, except that if the crack terminates at a fastener hole, stop drilling is not required.

(3) Any webs with cracks in excess of 3/4 inch and cracked webs which have been stop drilled on which further cracking occurs shall be repaired before further flight in accordance with Lockheed Service Bulletin 88/SB-579 or an equivalent approved by the Chief, Engineering and Manufacturing Branch, FAA Western Region.

(b) Following the accomplishment of (a) reinspect the area described in (a) in accordance with (a)(1) as follows:

(1) Inspect uncracked webs at intervals not to exceed 1,200 hours' time in service.

(2) Inspect stop-drilled cracks of 3/16 inch or less at intervals not to exceed 840 hours' time in service.

(3) Inspect stop-drilled cracks in excess of 3/16 inch but not greater than 1/2 inch at intervals not to exceed 420 hours' time inservice.

(4) Inspect stop-drilled cracks in excess of 1/2 inch but not greater than 3/4 inch at intervals not to exceed 210 hours' time in service.

(c) If cracks are detected by reinspection of (b)(1), repair in accordance with (a)(2) or (a)(3) as applicable. If additional cracking is detected by the reinspection of (b)(2) through (b)(4), repair in accordance with (a)(3).

(d) For aircraft on which the inspection and repair as required in (a) was accomplished before the effective date of this AD, such inspection may be considered as the initial inspection, and the repetitive inspection periods of (b) shall be computed from the aircraft's time in service at the time of that initial inspection.

(e) The periodic reinspection described in (b) may be discontinued when a cracked web is repaired in accordance with Lockheed Service Bulletin 88/SB-579 or an equivalent approved by the Chief, Engineering and Manufacturing Branch FAA Western Region, or when such repair is incorporated as a reinforcement on an uncracked web.

(f) Upon request of the operator, an FAA maintenance inspector, subject to prior approval of the Chief, Engineering and Manufacturing Branch, FAA Western Region, may adjust the repetitive inspection intervals specified in this AD to permit compliance at an established inspection period of the operator if the request contains substantiating data to justify the increase for such operator.

(Lockheed Service Information Letter 88/SIL-62 and Lockheed Service Bulletin 88/SB- 579 cover this same subject.)

This directive effective September 12, 1963.

Revised November 21, 1963.