52-14-02 CONVAIR: Applies to All 240 Airplanes With Hamilton Standard Propellers Except as Otherwise Indicated. Item IV Also Applies to All 340 Airplanes With Hamilton Standard Propellers.
Items I through IV are to be accomplished by means of a progressive modification program to be submitted to and approved by the FAA. This program shall begin no later than August 1, 1952, and shall be completed no later than August 1, 1953.
I. The following changes to the electrical circuits are to be accomplished: (NOTE: These changes apply to airplanes which have not been modified since they were manufactured. (See item II for modified airplanes):
A. Insulate exposed terminals at unfeathering relay, install insulating separator between throttle microswitches, and secure wires as specified in Convairogram No. 4, dated March 7, 1951.
II. To prevent inadvertent actuation of the reversing solenoid valves, the following changes to the electrical circuits are to be accomplished toprotect the reversing solenoid circuits from all other circuits and to protect the reversing solenoid circuits from each other: (NOTE: These changes are known to apply to some aircraft which were modified by operators so that they differ from the originally manufactured configuration. Other airplanes which have design features in the reversing solenoid circuits which are similar to those outlined below, but which are not specifically referred to in this list, should have these points protected in a manner equivalent to that described herein.)
A. Modify the following multiple pin connector assemblies as specified in item 2 of attachment A (see 52-13 for attachment A):
1. Connector at wing-fuselage disconnect.
2. Connector at Hamilton Standard Reversing box No. 80340 (covered by change specified in item C.)
B. Modify the following terminal strips as specified in item 1 of attachment A:
1. Terminal strip at firewall junction box.
2. Terminal strip in junction box at fuselage Station No. 109.
C. Hamilton Standard reversing relay box: Reversing solenoid circuit relay contacts, etc., to be shielded from all other circuits which are energized at any time except when reversing is desired. If reversing relay boxes are used which have separate pin connectors for the reversing solenoid wire and the remaining circuits, it shall not be possible inadvertently to interchange any connectors in the two relay boxes.
D. Reversing solenoid circuit wiring: Modify in accordance with item 4 of attachment A.
E. Protect the exposed terminals of the secondary throttle lock relays, (if used), as specified in item 3 of attachment A.
F. Install insulating separator between throttle microswitches, and secure wires as specified in Convairogram No. 4, dated March 7, 1951.
III. Other circuit modification: All airplanes are to be modified to comply with Hamilton Standard Service Bulletin No. 221.
IV. Reverse solenoid lock assembly on all airplanes which do not have "lift up" throttles, either (a) Install a warning light system as described in Convair Service Bulletin No. 240-381 except that the system shall be so arranged that it will indicate to the crew when the solenoid lock has just started to move to the open position, or (b) adjust the lock actuating handles so that not less than 1 inch of movement is required before the lock opens.
V. Maintenance practices (to be instituted not later than August 1, 1952):
A. At each nearest scheduled service to 350 hours:
1. Inspect all points specified in items I and IIB. The inspections of item IIB may be discontinued if the modifications made to the system are of the type described in item 1(a) or 1(b) of attachment A.
B. At any time that an electrical fault occurs in a circuit which is carried in the same bundles or the same conduits as the reversing solenoid circuit, representative terminal points in the faulty circuit are to be inspected to determine whether any damage may have occurred within the bundles or conduit. If there is evidence of possible damage, all the wiring involved is to be removed and inspected. Damaged wiring is to be replaced as necessary.
C. At each nearest scheduled service to 350 hours, perform an electrical check of the reverse safety switches in the pedestal assembly to assure that the switch is open when the throttles are moved forward out of the reverse position, unless it is shown that failure of any of the reverse safety switches to open will be clearly apparent to the flight crew by reason of improper operation of the propeller control system. Because of the many technical considerations involved, analyses showing that the objective of this revision has been accomplished should be referred to the FAA for engineering evaluation and approval.
D. At any time that operations are performed which may affect the relative position of the solenoid lock and throttle switches, but in anyevent at intervals not to exceed 1,500 hours: Check the relationship between the position of the pedestal strikers when they are: (a) In contact with the solenoid latch; (b) at the point where the detent roller contacts the first detent cam, and (c) when the reversing microswitches are actuated. It shall not be possible for the switches to be actuated before the latch and the detent engage the striker and the cam. This determination shall be made by positive measurements rather than observation of engine r.p.m. at which these actions take place.
VI. Operating instructions: Comply with item 5 of Attachment A, AD 52-13-02 Lockheed.
VII. (NOTE: Propeller governor design changes which are under development and whose purpose is to provide a high pressure hydraulic circuit bypass to safeguard against inadvertent reversing and ability to feather even when the reversing solenoid is energized, are still under consideration and may be the subject of a further directive.)