53-12-01: Horizontal Stabilizer Spar
FAA order 53-12-01 is an airworthiness directive. The FAA's subject line: Horizontal Stabilizer Spar. It names Hiller UH-12: about 217 aircraft on the U.S. register today, though an order usually covers particular versions or serial numbers rather than every one. System: airframe structure.
What it applies to as the FAA lists it
- Kind of product
- Aircraft
- Makes
- Hiller Aviation
- Models
- UH-12, UH-12A, UH-12B
- On this site
- Hiller UH-12 217 registered
Dates and paperwork
- Docket
- Unknown
- Status
- Current
- The FAA's document
- Read the order on the FAA's site
The order itself the regulatory text, as published
Show the full text (1,192 characters)
53-12-01 HILLER: Applies to All UH-12, UH-12A, UH-12B, HTE-1, HTE-2, H-23A and H-23B Helicopters Incorporating Horizontal Stabilizers With Short Spar Inserts or Without Spar Inserts.
Compliance required as indicated below.
Replacement of the horizontal stabilizer assembly, P/N 37001 on the above helicopters has been found necessary to prevent fatigue failure of the stabilizer spar.
(Hiller Service Bulletin No. 26 covers this procedure.)
(a) Stabilizer assemblies P/N 37001-9 incorporating short spar inserts (5.75 inches) must be removed from service when they have accumulated 300 hours total time. The replacement stabilizer is identified as 37001-14 and incorporates a long spar insert.
(b) Stabilizer assemblies P/N 37001-7 (without spar insert and identified as 37001) must be removed from service when they have accumulated 1,600 hours total time. The replacement stabilizer is identified as 37001-12 and incorporates a long spar insert.
(c) Stabilizer assemblies P/N 37001-12 and -14 incorporate long spar inserts (10.29 inches). Attachment to the aft bulkhead socket is made by two AN 174-17 bolts. The total service life of these assemblies is not limited.
Source: FAA Dynamic Regulatory System, airworthiness directives. The FAA's document is the authority; the register counts are this site's, from the FAA register of November 6, 2026. Connections as data: /graph/directive/53-12-01.json · aircraft systems.