AD 60-26-05

60-26-05 LOCKHEED: Amdt. 236 Part 507 Federal Register December 22, 1960. Applies to All 188 Series Aircraft.

Compliance required as indicated.

(a) Within the next 150 hours' time in service commencing on November 22, 1960, unless already accomplished within the last 300 hours' time in service, inspect the elevator counterweight installation, Lockheed Drawing No. 829912, at airplane center line for evidence of free play as follows: with elevator blocked at extreme down position apply up and down force to balance weight Lockheed P/N 827020-1, and measure total movement of balance weight due to cumulative free play in joints of balance arm linkage. If movement of balance weight due to cumulative free play in system exceeds 1/8-inch inspect each joint in balance arm linkage and reduce the free play by bolt and/or part replacement at one or more of these joints so as to reduce total free play movement of the balance weight to 1/16-inch or less prior to further flight. This inspection must be repeated every 450 hours' time in service. When provisions of paragraph (c)(1) are accomplished, this special inspection may be discontinued.

(b) Within the next 300 hours' time in service, unless already accomplished within the last 700 hours' time in service, and following any occurrence of inflight elevator or control column oscillations, inspect the elevator booster control valve viscous damper diaphragm, Lockheed P/N 813612-1 for evidence of rupture. See Lockheed Electra (Model 188) Overhaul Manual Section 27-1-10 Page 1 for information on evidence of rupture. If such evidence is found the airplane shall not be returned to service until the diaphragm is replaced with a new part, or compliance with paragraph (c)(2) has been accomplished. This inspection must be repeated at periods not to exceed 1,000 hours' time in service until the provisions of paragraph (c)(2) have been accomplished.

(c) The following must be accomplished within the next 1,000 hours' time in service.

(1) Install a spring-loaded cartridge, Lockheed P/N 840404-1, in the elevator counterweight linkage in the manner described by Lockheed Service Bulletin 88/SB-524.

(2) Replace the elevator boost control valve viscous damper, Lockheed P/N 813608-3, with an orifice type damper, Lockheed P/N 492508-3, in accordance with Lockheed Service Bulletin No. 88/SB-524.

(3) Rework the elevator booster assembly in accordance with Lockheed Service Bulletin No. 88/SB-524 to incorporate an orifice valve assembly, Lockheed P/N 804551-1, and modify the booster piston rod end installation to incorporate two retaining washers, Lockheed P/N 839756-1, in accordance with Lockheed Service Bulletin No. 88/SB-498.

(FAA approved Lockheed Service Bulletins 88/SB-498 and 88/SB-524, Lockheed Electra operating information letter No. 13 dated November 1, 1960, Lockheed Alert Bulletin No. 524 dated December 1, 1960, cover portions of this subject.)

This supersedes AD 60-24-02.

Thisdirective effective December 22, 1960.