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AD/GC-1/6 Engine Mount
Swift Museum Foundation GC-1A and GC-1B Swift Museum Foundation GC-1A and GC-1B Series Aeroplanes
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Swift Museum Foundation GC-1A and GC-1B Series Aeroplanes
| AD/GC-1/6 | Engine Mount | 18/2020 |
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| Applicability: | Swift Museum Foundation GC-1B model aircraft with standard engine mount Part Number 11-710-2520. |
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| Requirement: | 1. (a) Examine the engine mount members for evidence of rust and/or "pin holing" by probing with an ice pick or an equivalent tool.If the tubular member appears solid from the inspection described in 1.(a), remove the upper drive screw present in most engine mount legs, or drill a No. 37 size hole at this upper end of the engine mount member. Drill another No. 37 hole at the lower end of the member and check for the presence of rust, water or deterioration.(b) Replace any engine mount member that has been found to be damaged from internal corrosion by welding in a new member of 7/8 x 0.035 inch 4130 steel heat treated to 85,000 p.s.i. yield. Drill No. 37 holes in each end of this new member. Fill any new or existing member with Lionoil (or equivalent slushing compound) and then drain. The No. 37 holes can be used for this purpose. After the slushing compound has been drained out of the member, plug the holes with drive screws, AN 535-4-3.Note 1: No exact method exists in the field for measuring the wall thickness remaining at the lower end of the tube, or of determining the exact amount of wall deterioration through rusting, but a close visual inspection of the drilled hole coupled with the condition encountered (i.e., obvious presence of water or rust) will allow a reasonable judgment of the general condition. For example, after the hole is drilled, the presence of a heavy colloidal solution of rust in water would indicate the probability of serious deterioration. An air nozzle may be applied at the upper hole to facilitate the expelling of any moisture that may be present.Note 2: United States of America Federal Aviation Administration (FAA) AD 64‑05‑06 is the source document for the requirements of this AD. |
| Compliance: | 1. Unless previously accomplished, within 6 months after the commencement date of this AD and thereafter at each 100 hours’ time in service or every 12 months, whichever occurs first. |
| This AD commences on 17 September 2020. |
| Background: | There have been instances of failure through internal corrosion of the upper left and right hand members of the engine mount assembly, the point of failure being just above the weld junction with the horizontal members of the engine mount. This AD is issued to preclude the possibility of failures on Australian registered aircraft, which could result in the loss of the engine.An audit of the Australian Aircraft Register found that Swift Museum Foundation GC-1B aircraft have been on the register for some time and that requirements equivalent to the applicable FAA ADs have not previously been mandated in Australia for these aircraft.This AD mandates requirements equivalent to FAA AD 64-05-06. |
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