# AD 50-09-01: Stabilizer Spar Fittings and Shims - Type: Airworthiness directive - Status: Current - Products: Boeing AT-6 (SNJ-2), AT-6A (SNJ-3), AT-6B, AT-6C (SNJ-4) and BC-1A - Superseded by: Nothing supersedes this AD - Product type: Aircraft, Small airplane - Registered aircraft: 107 may be affected, by airframe or engine model (OpenAirDocs) - FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/D1595A2361D5F4D686256A450068CE7C.0001 - DRS record last changed: May 30, 2024 - Page: https://openairdocs.org/ad/50-09-01 ## The airworthiness directive 50-09-01 NORTH AMERICAN: Applies to all Army Model BC-1A, AT-6, -6A, -6B, - 6C; Navy SNJ-2, -3 and -4 Aircraft. To be accomplished prior to original certification. Inspect the horizontal stabilizer rear spar connection for cracked fittings and the installation of shims as follows: (1) Remove the fuselage to vertical stabilizer fairing assembly and the rear fairing assemblies at the horizontal stabilizer. (2) Remove the 1/4-inch bolts which attach the rear spar connection fitting to the spar assembly. (3) Remove paint from connection fittings and inspect for cracks. Check with a machinist's square or other means to determine if fitting is preset. Replace any cracked or preset fitting and repaint all others. New fittings may be made of 24 ST or X4130 bar stock to the same dimensions as the old fittings. (4) Inspect the fit between the spar and the sides of the base fitting with a feeler gage. Also inspect the fit between fitting P/N 77-21021 and the spar. If gaps exist, shims are necessary. (5) Fabricate 24ST shims 3 1/8 inches x 15/16 inch and of necessary thickness, and place on either side of spar flanges maintaining a parallel overall dimension to fit inside of fitting P/N 77-21021 within maximum clearance of 0.010. (6) Drill holes through the shims to match those in the fitting. Remove all chips and reinstall the various parts. (North American Service Bulletin dated March 6, 1946, covers this subject also.) This supersedes AD 45-44-03. ## 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 5 of 9 models: AT-6A (SNJ-3), BC-1A, 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: 107 (107 by airframe model, 0 by engine model) - Makers: North American 82, 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/Walker/Screws 1 Models with the most aircraft: - [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/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 / 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) All 12 models: https://openairdocs.org/ad/50-09-01/models.md Every aircraft: https://openairdocs.org/ad/50-09-01/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.