60-11-03 LOCKHEED: Amdt. 159 Part 507 Federal Register May 24, 1960. Applies to All 188 Series Aircraft.
Compliance required as indicated.
Due to loose attachments and cracked quick engine change upper cowl panel longerons the following inspections are required.
Prior to dispatch from a terminal where inspection facilities are available, unless already accomplished within the last 300 hours' time in service, and thereafter at every 300 hours' time in service, inspect the top cowl panel upper longerons and the attachments at the rear fittings for cracks or loose attachments.
(a) Replace loose attachments in the longeron fittings. Acceptable replacements are:
(1) One-sixty-fourths-inch diameter oversize Hi-Lok (P/N HL 56-6 pin, P/N HL 64-6-5 pin, P/N HL 85-6 collar).
(2) Thirteen-sixty-fourths-inch diameter NAS type close tolerance screw, minimum heat treat 160,000 p.s.i. Ream to oversize hole limits of 0.212-0.2192-inch diameter.
(3) Seven-thirty-seconds-inch diameter NAS type close tolerance screws; minimum heat treat 160,000 p.s.i.; minimum edge distance, 1 1/2 diameters. Ream to oversize hole limits of 0.2181-0.2192-inch diameter.
(4) It is satisfactory to mix Huck bolts and Hi-Lok fasteners, but it is not acceptable to mix NAS type screws with Huck bolts or Hi-Lok fasteners.
(b) Cracked longerons must be replaced or an FAA approved repair incorporated before next flight.
The preceding inspections may be discontinued after the incorporation of the modifications contained in Lockheed Service Bulletin 88/SB-500.
(Lockheed Alert Service Bulletin No. 467 covers this same subject.)
This airworthiness directive sent by telegram to all operators of 188 aircraft on April 29, 1960.
Revised September 29, 1960.
Revised May 13, 1961.