AD 57-14-03

57-14-03 VICKERS: Applies to All Viscount 700 Series Aircraft.

Compliance required as indicated.

Investigation of a recent case resulting in asymmetric flaps occurring just prior to touchdown shows excessive end float of the flap torque shaft can occur between the flap gearbox and No. 1 flap unit port and starboard. Following action considered essential by Vickers with which the FAA concurs and considers mandatory.

1. At next daily inspection unscrew flap universal joint cap port and starboard and check engagement of trunnion blocks within universal joint body of the torque tube. With trunnion block journals facing fore and aft ensure maximum outboard float of torque shaft is obtained by gentle tapping if necessary. Where trunnion blocks do not protrude from body more than 0.4 of an inch, aircraft may continue to fly but corrective action (item 3.) must be taken within 300 hours flying.

2. If trunnion blocks protrude more than 0.4 of an inch, corrective action (item 3.) must be taken within 25 hours flying time, or if trunnion blocks protrude 0.52 of an inch or more, corrective action must be taken prior to further flight.

3. Set torque shaft with trunnion blocks flush with end of universal body and prepare and fit tubular fiber or fluon (teflon equivalent) distance piece to suit dimension between inboard vertical face of No. 1 flap unit chain box and adjacent end of torque tube. Internal diameter of distance piece 1.52 inches with suitable recess to clear greaser on chain box if necessary. Before removal, splined shaft must be marked to ensure correct reassembly. On completion of inspection torque tubes should be moved toward gearbox as far as end float permits.