| AD Number | 57-14-01 | Status | Active |
| Effective Date | Not specified | Issue Date | Not specified |
| Docket Number | Unknown | Amendment | N/A |
| Product Type | ["Aircraft"] | Product Subtype | ["Large Airplane"] |
| CFR Part | --- - Part 39 | CFR Section | N/A |
| Citation | This information is not available. | ||
| Manufacturer(s) | Kelowna Flightcraft R & D Ltd. |
| Model(s) | 240 Series 340 |
57-14-01 CONVAIR: Applies to All 240/340 Series Aircraft.
Compliance required as soon as possible but not later than September 1, 1957, unless already accomplished.
Investigation of a recent Convair Model 340 accident where the nose gear stuck in the retracted position showed failure of the nose landing gear drag strut pivot shaft sleeve, Convair P/N 240-5257112 to be the cause. Examination of the failed part showed that the 1.06-inch counterbore was drilled beyond acceptable limits, allowing a fatigue crack to develop at the relief radius undercut of the shoulder of the bearing surface at the threaded end. As a result of these findings the following inspection or equivalent method to determine that satisfactory parts are installed should be conducted on all Model 240/340 Series aircraft incorporating nose landing gear pivot shaft sleeve P/N 240-5257112.
Inspection can be accomplished by removal of the forward left tunnel door at Station 52 for access to the threadedend of the sleeve. The threaded portion of the sleeve may be either 1 inch or 1.6 inches long. Using a depth gage through the pilot hole in the threaded end of the sleeve, measure the distance from the threaded end of the sleeve to the intersection of the pilot hole and the bottom of the 1.06-inch diameter counterbore made by the cutting surface of the counterbore drill. For sleeves with a long threaded end (1.6 inches) a minimum distance of 4.1 inches is permissible. On sleeves with a short threaded end (1.00 inch) a minimum distance of 3.5 inches is permissible. Any sleeve with dimensions less than specified above should either be replaced or be further inspected as outlined in the next paragraph. If it is desired to inspect the sleeve from the end opposite to the threaded end, the distance from the end of the sleeve to the intersection of the pilot hole and the bottom of the 1.06-inch counterbore hole should not exceed 8.38 inches.
Parts found to be unsatisfactory as a result ofthe above inspections should be X-rayed or removed for further inspection and magnaflux. If the part shows no evidence of cracks and the material between the end of the counter drill 1.06-inch diameter hole and the relief radius undercut in the shoulder at the bearing surface is greater than 0.350 inch, the part has adequate strength and may be reinstalled. The 0.350-inch dimension is considered to be the perpendicular distance from the end of the counterbore.
(Angle surface caused by the counterbore cutting surface and the relief radius cutout. Convair Service Airgram subject "Nose Landing Gear Pivot Shaft Sleeve" dated May 13, 1957, contains similar information.)