AD 2022-20-14 Airworthiness Directives; Bell Textron Inc., Helicopters and Various Restricted Category Helicopters

Makes named: robinson. Models named: 204B, 205A, 205A-1, 205B, 210, 212, 412, 412CF, 412EP, HH-1K. Read the applicability below — it usually turns on serial or part numbers too.

This AD applies to the following: (1) Bell Textron Inc., Model 204B, 205A, 205A-1, 205B, 210, 212, 412, 412CF, and 412EP helicopters, certificated in any category; and (2) Various restricted category helicopters: (i) Model HH-1K helicopters; current type certificate holders include, but are not limited to, Rotorcraft Development Corporation; (ii) Southwest Florida Aviation International, Inc., Model SW205A-1 helicopters; (iii) Model TH-1F helicopters; current type certificate holders include, but are not limited to, Robinson Air Crane Inc.; Rotorcraft Development Corporation; and Tamarack Helicopters, Inc.; (iv) Model TH-1L helicopters; current type certificate holders include, but are not limited to, Bell Textron Inc.; Overseas Aircraft Support, Inc. (type certificate previously held by JTBAM, Inc.); and Rotorcraft Development Corporation; (v) Model UH-1A helicopters; current type certificate holders include, but are not limited to, Richards Heavylift Helo, Inc.; (vi) Model UH-1B helicopters; current type certificate holders include, but are not limited to, International Helicopters, Inc.; Overseas Aircraft Support, Inc.; Red Tail Flying Services, LLC; Richards Heavylift Helo, Inc.; Rotorcraft Development Corporation; Southwest Florida Aviation International, Inc.; and WSH, LLC (type certificate previously held by San Joaquin Helicopters); Note 1 to paragraph (c)(2)(vi): Helicopters with an SW204 or SW204HP designation are Southwest Florida Aviation International, Inc., Model UH-1B helicopters. (vii) Model UH-1E helicopters; current type certificate holders include, but are not limited to, Bell Textron Inc.; Overseas Aircraft Support, Inc.; Rotorcraft Development Corporation; Smith Helicopters; and West Coast Fabrications; (viii) Model UH-1F helicopters; current type certificate holders include, but are not limited to, AST, Inc.; California Department of Forestry; Robinson Air Crane, Inc.; Rotorcraft Development Corporation; and Tamarack Helicopters, Inc.; (ix) Model UH-1H helicopters; current type certificate holders include, but are not limited to, Arrow Falcon Exporters, Inc.; Global Helicopter Technology, Inc.; Hagglund Helicopters, LLC; JJASPP Engineering Services LLC; Northwest Rotorcraft, LLC; Overseas Aircraft Support, Inc.; Richards Heavylift Helo, Inc.; Rotorcraft Development Corporation; Southwest Florida Aviation International, Inc.; and Tamarack Helicopters, Inc.; Note 2 to paragraph (c)(2)(ix): Helicopters with an SW205 designation are Southwest Florida Aviation International, Inc., Model UH-1H helicopters. (x) Model UH-1L helicopters; current type certificate holders include, but are not limited to, Bell Textron Inc.; Overseas Aircraft Support, Inc.; and Rotorcraft Development Corporation; and (xi) Model UH-1P helicopters; current type certificate holders include, but are not limited to, Robinson Air Crane, Inc.; and Rotorcraft Development Corporation.

Comply with this AD within the compliance times specified, unless already done.

(1) Within 3,000 hours time-in-service (TIS) accumulated by the main transmission after the effective date of this AD, and thereafter at intervals not to exceed 3,000 hours TIS accumulated by the main transmission, remove the screws and washers from the upper and lower surfaces of the main transmission support case lateral mounts and accomplish the following: (i) Visually inspect each screw for corrosion and thread damage. If there is any corrosion or thread damage, before further flight, remove the screw from service. (ii) Visually inspect each upper and lower washer for corrosion and pitting. (A) If there is any corrosion or pitting that exceeds 10% of any surface or is deeper than 0.01 inch (0.3 mm), before further fight, remove the washer from service. (B) If there is any corrosion or pitting that is 10% or less of any surface or has a depth of 0.01 inch (0.3 mm) or less, before further flight, remove the washer from service or repair the washer in accordance with FAA-acceptable methods. (iii) Visually inspect each installed bushing for corrosion and pitting. (A) If there is any corrosion or pitting inside the bushing bore that exceeds 10% of the surface or is deeper than 0.005 inch (0.13 mm), or if there is any corrosion or pitting on the bushing flange or chamfer that exceeds 10% of the surface or is deeper than 0.01 inch (0.3 mm), before further fight, remove the bushing from service. (B) If there is any corrosion or pitting inside the bushing bore that is 10% or less of the surface or has a depth of 0.005 inch (0.13 mm) or less, or if there is any corrosion or pitting on the bushing flange or chamfer that is 10% or less of the surface or has a depth of 0.01 inch (0.3 mm) or less, before further fight, remove the bushing from service or repair the bushing in accordance with FAA-acceptable methods. (iv) Visually inspect each upper and lower main transmission support case lateral mount machined surface adjacent to each washer and each lateral mount threaded screw hole for corrosion and mechanical damage. For the purposes of this AD, mechanical damage may be indicated by a crack or pitting. (A) Before further flight, remove the main transmission support case assembly from service if any of the following exist: ( 1 ) The depth of any pitting exceeds 0.03 inch (0.8 mm), ( 2 ) The area of pitting for each pad surface exceeds 0.75 square inch (483.87 square mm) or exceeds 50% of any 0.50 inch (12.7 mm) diameter, or ( 3 ) Any mechanical damage to the threaded holes (8-32 NC-2B x 0.62 deep) exceeds 1 thread depth. (B) Before further flight, remove the main transmission support case assembly from service or repair the main transmission support case assembly in accordance with FAA-acceptable methods, if any of the following exist: ( 1 ) The depth of any pitting is 0.03 inch (0.8 mm) or less. ( 2 ) The area of pitting for each pad surface is 0.75 square inch (483.87 square mm) or less, or 50% or less of any 0.50 inch (12.7 mm) diameter, or ( 3 ) Any mechanical damage to the threaded holes (8-32 NC-2B x 0.62 deep) has a depth of 1 thread or less. (2) Fluorescent penetrant inspect (FPI) all surfaces of the main transmission support case lateral mounts for a crack at the compliance times identified in paragraph (g)(2)(i) or (ii) of this AD. (i) For helicopters with a main transmission that has accumulated 6,000 or more total hours TIS, within 300 hours TIS after the effective date of this AD, unless already done within the last 6,000 hours TIS. (ii) For helicopters with a main transmission that has accumulated less than 6,000 total hours TIS, before accumulating 6,300 total hours TIS on the main transmission. (iii) If there is any crack, before further flight, remove the main transmission support case assembly from service. (3) Thereafter following paragraph (g)(2) of this AD, at intervals not to exceed 6,000 hours TIS accumulated by the main transmission, FPI all surfaces of the main transmission support case lateral mounts for a crack. If there is any crack, before further flight, remove the main transmission support case assembly from service.

This AD was prompted by reports of cracks found in the main transmission support case possibly due to corrosion. The FAA is issuing this AD to detect and address corrosion and other mechanical damage of the main transmission support case assembly. The unsafe condition, if not addressed, could result in cracking at the upper or lower surfaces of the lateral mounts, loss of load carrying capabilities of the main transmission, and subsequent loss of control of the helicopter.

None.