Landing Gear: DC-3 Tail Wheel Fork Check

1

FAA Aircraft Certification Service SPECIAL AIRWORTHINESS INFORMATION BULLETIN SUBJ: Landing Gear: DC-3 Tail Wheel Fork Check SAIB: NM-08-28 Date: June 12, 2008 This is information only. Recommendations aren’t mandatory.

Introduction

This Special Airworthiness Information Bulletin (SAIB) advises you, owners and operators of all McDonnell Douglas Corporation Model DC3-G102, DC3-G102A (Army C-49E, C-50, C-50A, C-50B, C-50C, C-50D, C-51), DC3-G103A, DC3-G202A (Army C-49, C-49A, C-49B, C-49C, C- 49D, C-49J, C-49K; Navy R4D-2), DC3A-SCG, DC3A-SC3G, DC3A-S1CG, DC3A-S1C3G (Army C-41, C-41A, C-48, C-48A, C-52, C-52A, C-52B, C-52C, C-53, C-53B, C-53C, C-53D, C- 68; Navy R4D-3, R4D-4), DC3A-S4C4G, DC3C-SC3G, DC3C-S1C3G, -S4C4G (Army C-47, C- 47A; Navy R4D-1, R4D-5), DC3C-R-1830-90C (Army C-47B, Navy R4D-6), DC3D-R-1830-90C (Army C-117A) airplanes, to inspect for cracks initiating from the fairing attachment holes in the tail wheel fork.

Background

On February 25, 2008, we received a report indicating that a Model DC-3C (produced as a C-47A) airplane experienced failure of the tail wheel fork during rollout after landing. The airplane suffered structural damage to the bottom of the fuselage immediately adjacent to the tail wheel area. Subsequent inspection revealed that the tail wheel fork, part number 5115862, had failed. Review of the failed part indicated that a crack had initiated at a threaded fastener hole for the tail wheel strut fairing. Discoloration in the vicinity of the failure suggested the crack was present for some time. In this case, the fairing was not installed but the two attachment screws were in place. The airplane had accumulated 19,482 total flight hours. Currently, there is no specific inspection requirement of the tail wheel area.

Recommendations

Although none have been reported, failure of the tail wheel fork in flight could result in loss of the tail wheel. To minimize the possibility of fatigue crack initiation and propagation to failure of the fork, we recommend the following be accomplished:

1. Perform visual inspections of the fairing attach screw hole areas of the tail wheel fork for cracks (under proper lighting, with a 10X-20X magnifying glass, with the fairing and screws removed, and the area properly cleaned); and 2. Assure that appropriate screws are installed in the fairing attach screw holes before returning the airplane to service following the crack inspection.

Note that the inspection may be accomplished during other maintenance activities, such as a scheduled lubrication of the tail wheel fork bearings. We also recommend that the inspection be repeated on an annual basis, which can greatly reduce downtime and cost of repair due to collateral damage from a fatigue failure.

2 For Further Information Contact

David Y. J. Hsu, Aerospace Engineer Los Angeles Aircraft Certification Office, ANM-120L 3960 Paramount Blvd., Lakewood, CA 90712 Telephone: (562) 627-5323; fax: (562) 627-5210; Email: [email protected]