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Complete Aviation Regulatory Library
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DataBases updated: Mar 9th, 2026
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Service Bulletins
NameRevisionLangSubjectDate
2 en Control System Integrity12/20/1999
en Mandatory Collective Pitch Ballast System - Bracket Assembly P/N 31125-1 - Inspection and Possible Rework of6/23/1951
en Main Rotor Blade Incidence Arm - Part No. 31114-112/11/1951
en Mandatory Replacement of 37001-7 and 37001-9 Stabilizer Assemblies4/9/1953
en Mandatory Inspection and Replacement of Main Rotor Drag Strut Pin - P/N 51414-14/7/1953
3 en Inspection and Rework of Control Rotor Assemblies10/24/1979
A en Installation of Improved CR-10U Slip Joint Cam Follower Rollers5/15/1956
A en Installation of Tail Boom Aft Bulkhead8/23/1955
A en Replacement of Cyclic Scissors, Gimbal Ring and Control Rotor Bracket2/15/1956
en Main Rotor Assembly - Inspection of Main Rotor Drag Strut1/21/1974
en Main Rotor Blades P/N 2253-1101-03 and 04 - Replacement of P/N 2253-1124 Anti-Node Bar Assembly9/26/1978
en Inspection of Main Rotor Blade Anti-Node Bars1/22/1980
rev en Main Rotor Assembly - Inspection of P/N 2253-1101-04 Main Rotor Blades for Cracks in Steel Spar and Bond Separation12/19/1985
en Main Rotor Assembly - Sealing of P/N 53200-03 Main Rotor Blades3/25/1981
en Main Rotor Assembly - Addition of Shims at Drag Strut Terminal4/8/1983
A en Installation of 55003-1 Tension-Torsion Bar and A-1403-3 Bushings5/6/1958
A en Installation of 55003-1 Tension-Torsion Bar and A-1403-3 Bushings6/12/1956
en Installation of Fuel Shutoff Control Safety Stop6/17/1977
B en Replacement of Stabilizer Assembly and Incorporation of Stabilizer Strut Installation12/3/1958
en Installation of Tail Rotor Laminated Tension-Torsion Bar and Blade Assembly5/15/1958
en Wobble Plate Shield Modification10/16/1959
en Wobble Plate Shield Modification10/16/1959
en Modification to Improve Lubrication in Main Transmission, UH-12D/E2/26/1962
Service Information Letters
NameRevisionLangSubjectDate
en 63100-2 Lower Frame Assembly (Engine Mount), or Mount Modified in Accordance with Service Bulletin No. 5111/30/1956
C en Transmission Gear Inspection4/27/1964
C en Inspection of Main Rotor Blades (2253-1101-03 only) on all UH-12D, UH-12E, UH-12F and UH-12G Helicopters2/15/1966
en Inspection of Mercury Clutch Sideplates7/20/1966
A en Inspection of Cyclic Bracket Installation and Replacement of Cyclic Bracket Attach Bolts and Inserts4/5/1967
en Inspection of Mercury Clutch Sideplates7/20/1966
Service Letters
NameRevisionLangSubjectDate
en Inspection of Main Rotor Outboard Tension-Torsion Bar Pin P/N 51452.3/31/1978
A en Bonding Examination of Main Rotor Blade Doubler Area6/11/1979
en Tail Rotor Assembly - Inspection of Tail Rotor Yokes3/20/1969