# AD 50-38-01: Fuselage Structure Corrosion - Type: Airworthiness directive - Status: Current - Products: Boeing AT-6 (SNJ-2), AT-6A (SNJ-3), AT-6B, AT-6C (SNJ-4), AT-6D (SNJ-5) and AT-6F (SNJ-6) - Superseded by: Nothing supersedes this AD - Product type: Aircraft, Small airplane - Registered aircraft: 220 may be affected, by airframe or engine model (OpenAirDocs) - FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/1C69BCCB7F9587A186256A45006A85F3.0001 - DRS record last changed: May 30, 2024 - Page: https://openairdocs.org/ad/50-38-01 ## The airworthiness directive 50-38-01 NORTH AMERICAN: Applies to All Model AT-6 Series Aircraft. To be accomplished at the next annual inspection and at each succeeding annual inspection thereafter. Several recent incidents have indicated that the inspections presently required are not sufficiently comprehensive to reveal all areas of the airplane which may have been adversely affected by intergranular corrosion, and that the required inspections should be repeated periodically. Accordingly, in order to minimize the possibility of structural failure due to such corrosion, the following must be accomplished: Inspect all accessible structural aluminum alloy components for evidence of intergranular corrosion particularly in the following locations: At the upper and lower deck and the most forward and two aft bulkheads in the monocoque fuselage; frame around the baggage door; inboard end of horizontal stabilizer spars; fuel cell doors in the wing center section; wing attach angles; two inboard ribs oneach outer wing; trailing edge ribs above flaps; and the outboard rib of the wings, especially at the trailing edge. Full use should be made of all access provisions to accomplish as thorough an inspection as possible. In conducting these inspections, full reliance cannot be placed on visual examination alone. A screwdriver or other instrument should be used to explore for dull sounding areas and for material which may be penetrated easily by pressure applied to the screwdriver tip or similar sharp point. Areas adjacent to joints and sheared edges should be examined thoroughly. Formed material in particular has been found to be subject to rapid intergranular corrosion, because of poor heat treatment of parts, which were formed in the annealed condition, and later heat treated. All corroded parts must be replaced. This supersedes AD 47-41-01. ## Affected data sheets (1) (OpenAirDocs) The type certificate data sheets whose models the AD names. - [TCDS A-2-575](https://openairdocs.org/tcds/A-2-575): The Boeing Company; names 6 of 9 models: AT-6F (SNJ-6), AT-6D (SNJ-5), AT-6A (SNJ-3), AT-6C (SNJ-4), AT-6 (SNJ-2), AT-6B ## Registered aircraft it may apply to (OpenAirDocs) Matched by airframe and engine model; the AD's applicability may narrow it by serial number, part number or equipment. - Aircraft: 220 (220 by airframe model, 0 by engine model) - Makers: North American 191, North American/Victoria MNT LT 20, North American / Crosser G 1, North American-Collins 1, North American/Case M V JR 1, North American/Levrett 1, North American/Medore ART 1, North American/Medore Arthur 1, North American/Sawyer 1, North American/Schwamm 1 Models with the most aircraft: - [North American AT-6D](https://openairdocs.org/model/north-american-at-6d): 87 aircraft (airframe model) - [North American AT-6C](https://openairdocs.org/model/north-american-at-6c): 43 aircraft (airframe model) - [North American AT-6](https://openairdocs.org/model/north-american-at-6): 28 aircraft (airframe model) - [North American AT-6F](https://openairdocs.org/model/north-american-at-6f): 22 aircraft (airframe model) - [North American/Victoria MNT LT AT-6A](https://openairdocs.org/model/north-american-victoria-mnt-lt-at-6a): 20 aircraft (airframe model) - [North American AT-6A](https://openairdocs.org/model/north-american-at-6a): 5 aircraft (airframe model) - [North American AT-6B](https://openairdocs.org/model/north-american-at-6b): 3 aircraft (airframe model) - [North American AT-6C(SNJ-4)](https://openairdocs.org/model/north-american-at-6c-snj-4): 3 aircraft (airframe model) - [North American-Collins AT-6A](https://openairdocs.org/model/north-american-collins-at-6a): 1 aircraft (airframe model) - [North American/Walker/Screws AT6C](https://openairdocs.org/model/north-american-walker-screws-at6c): 1 aircraft (airframe model) - [North American/Schwamm AT-6F](https://openairdocs.org/model/north-american-schwamm-at-6f): 1 aircraft (airframe model) - [North American/Medore Arthur AT6-D](https://openairdocs.org/model/north-american-medore-arthur-at6-d): 1 aircraft (airframe model) - [North American/Medore ART NA AT6-F](https://openairdocs.org/model/north-american-medore-art-na-at6-f): 1 aircraft (airframe model) - [North American / Crosser G AT6A](https://openairdocs.org/model/north-american-crosser-g-at6a): 1 aircraft (airframe model) - [North American/Levrett AT6-C](https://openairdocs.org/model/north-american-levrett-at6-c): 1 aircraft (airframe model) - [North American/Case M V JR AT-6](https://openairdocs.org/model/north-american-case-m-v-jr-at-6): 1 aircraft (airframe model) - [North American/Sawyer NORTH AMER AT-6D](https://openairdocs.org/model/north-american-sawyer-north-amer-at-6d): 1 aircraft (airframe model) All 18 models: https://openairdocs.org/ad/50-38-01/models.md Every aircraft: https://openairdocs.org/ad/50-38-01/aircraft.md Its text cites no advisory circulars or STCs. --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.