Description
U.S. Army M21 Huey Gun-Deflection Torque Stop, P/N 7792430, NSN 1005-00-974-9715
Item Overview
This original U.S. Army gun-deflection torque stop was used in the M21 helicopter armament subsystem installed on UH-1B and UH-1C Huey gunships.
The stop fits inside the deflection housing of either the left- or right-hand mechanical gun-drive assembly. In this application, “deflection” means the lateral or traverse movement of the gun mount.
Army Technical Manual TM 9-1090-202-35P identifies this exact component as Figure 33, Item 98. The part is listed on printed page 74 and shown within the mechanical gun-drive assembly on printed page 143.
Identification and Features
- Official item name: Stop, Torque, Gun Deflection
- Federal Stock Number: 1005-974-9715
- Later National Stock Number: 1005-00-974-9715
- Part/drawing number: 7792430
- Manual reference: TM 9-1090-202-35P
- Figure and item number: Figure 33, Item 98
- Parent system: M21 helicopter armament subsystem
- End-item NSN: 1090-00-923-5971
- Aircraft application: UH-1B and UH-1C Huey
- Installation: Left- or right-hand mechanical gun-drive deflection housing
- Material: Corrosion-resistant steel made to AMS 5643
- Heat treatment: H-1025 condition
- Hardness: Rockwell C35–42
- Finish: Passivated
- Cataloged length: 3.820"
- Cataloged diameter: 0.623"
- Through-hole diameter: 0.375"
- Package quantity: 1 EA
- Army contract marking: DAAF05-67-M-1069
- Package date: May 1967
- Status: Inert mechanical hardware
Function
The torque stop was part of the mechanism that controlled the gun mount’s side-to-side travel. It was installed inside the deflection housing of the mechanical gun drive.
Based on its hardened construction, shape, and mounting location, the part appears to provide a solid reaction or end stop that absorbs drive torque near the mount’s travel limit. This specific end-stop action is an informed interpretation of its design and location.
The M21 also used a separate electrical deflection-limit switch. This torque stop is not that switch, an electrical firing interlock, or a gun component.
Historical Background
The M21 was a major U.S. Army helicopter armament system of the Vietnam War. It was used on UH-1B and UH-1C Huey gunships to provide close support, escort troop-carrying helicopters, and attack ground positions.
The system combined paired 7.62mm M134 Miniguns with seven-tube 2.75-inch rocket launchers. The guns were carried in movable mounts that could be aimed in elevation and deflection. Mechanical drive assemblies moved the mounts and held them within their designed travel limits.
Small internal parts such as this torque stop helped the drive system operate safely and withstand repeated movement, vibration, and mechanical load. The May 1967 package date places this example within the active Vietnam War production and support period for Huey gunships.
Package Markings
The original box is marked “STOP, TORQUE, GUN-DEFL.” and identifies one part under FSN 1005-974-9715. That number was later written in the modern NSN format as 1005-00-974-9715.
Contract number DAAF05-67-M-1069 identifies a fiscal-year-1967 Army procurement. The package is dated 5/67, or May 1967.
Condition
This is an original military-surplus mechanical component in period packaging. The part may show storage residue, discoloration, light surface marks, or other signs of age. The box may have fading, stains, creases, tears, handwriting, or shelf wear.
Operational fitness has not been tested or guaranteed. Please review the product pictures for the represented condition, markings, and included contents.
Ideal For
- UH-1B and UH-1C Huey restoration projects
- M21 helicopter armament-system displays
- M134 Minigun mount research
- Vietnam War aviation collections
- Military helicopter parts collections
- Springfield Armory equipment research
- Museums and educational exhibits
- Original military packaging collections
This listing is for one gun-deflection torque stop only. The mechanical gun-drive assembly, deflection housing, M134 Minigun, rocket launcher, helicopter, electrical limit switch, and other components are not included unless specifically pictured or stated.
Approx length 4", Approx width 1", Approx height 1", Approx weight lbs.
Pictures are stock images of our inventory. Unless otherwise noted, you will not be receiving the exact item shown in the pictures. The pictures are representative of the item’s general condition. The item you receive might be slightly better, or worse, condition than was shown in the pictures.
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