74-26-08 ROCKWELL INTERNATIONAL: Amendment 39-2051. Applies to NA265- 40, NA265-60, NA265-70 (CT-39E, CT-39G) series airplanes certificated in all categories.
Compliance required as indicated.
To preclude inflight engine shutdown due to loss of oil quantity because of an unknown incipient failure condition in the engine oil low pressure switch, (Hydra-electric, P/N 12252), accomplish the following:
(1) Within ten flight hours after receipt of this AD, unless already accomplished, inspect each engine installation to determine if Hydra-electric P/N 12252, is installed. If found installed remove Hydra-electric P/N 12252 and;
(a) Replace with Hydra-electric P/N 12252-1, or,
(b) Install Aero Instruments Co. P/N 1B2522-230, or Century Electronics and Instrument Inc. P/N 1B2522-230; or
(c) Install O-ring NAS 617-4 and plug MS 9015-04 or an 814-4L. Safety wire with proper lockwire. Disconnect the electric connector cap, and stow in accordance with good maintenance practice. See (d)(ii) and (e) below for placard installation.
(d) If both engine oil low pressure switches are removed and plugged;
(i) The amber "OIL PRESS LOW" caution light must be modified by either removing the light cover and replacing with a blank cover or installing an "INOPERATIVE" placard over the light cover, and,
(ii) Install, in front of and in full view of the crew, a placard which reads: "ENGINE LOW OIL PRESSURE WARNING SYSTEM INOPERATIVE. MONITOR OIL PRESSURE GAGES."
(e) If one engine oil low pressure switch is removed and plugged, install in front of and in full view of the crew, a placard which reads: "(LEFT OR RIGHT) ENGINE LOW OIL PRESSURE WARNING SYSTEM INOPERATIVE. MONITOR (LEFT OR RIGHT) OIL PRESSURE GAGE." Note: Sabre Gram, dated November 15, 1974, covers this subject.
(2) Within sixty days after receipt of this AD, install new engine oil low pressure switch, Hydra-electric P/N 12252-1 or Aero Instruments Co. or Century Electronics and Instrument Inc. P/N 1B2522-230, in those positions where Hydra-electric P/N 12252 was removed, and plugs have been installed. Reconnect the electrical connector and accomplish functional check before return to service.
(3) Remove placards and reactivate "OIL PRESS LOW" caution light when (2), above, has been accomplished.
(4) Airplanes may be flown to a base for the performance of the inspections and installations required by paragraph one of this AD, per FAR's 21.197 and 21.199.
(5) Return P/N 12252 switches removed from service to Rockwell-International, Aviation Service Division, Lambert Field, St. Louis, Mo. 63l45
(6) Equivalent inspections and installations may be approved by the Chief, Aircraft Engineering Division, FAA Western Region, upon submission of adequate substantiating data."
This amendment is effective December 24, 1974, for all persons except those to whom it was made effective immediately by airmail letter dated November 27, 1974.