SH247NW
Installation and maintenance of exhaust ejector engine oil cooler system. (UH-12D (ARMY UH-23D modified per STC SH177WE). Held by Siam Hiller Holdings INC, which holds 27 approved modifications in all. Last revised August 19, 2005. System: engine.
What it applies to
- Kind of product
- Aircraft
- Design holder
- Hiller Aviation
- Models
- UH-12D (Army UH-23D)
- Type certificate
- 4H10
- On this site
- Hiller UH-12 217 registered
- The FAA's record
- On the FAA's site
What an approved modification is
A supplemental type certificate is the FAA's approval of a change to a certified design: a new engine or propeller, avionics, an autopilot, floats, a parachute, a larger fuel tank, an ice-protection kit. The company holding it may sell the kit and the paperwork to owners of the listed models; the modification then becomes part of that aircraft's record. The FAA's list says what was approved and for which models, not how many aircraft carry it.
Source: FAA supplemental type certificates (Dynamic Regulatory System). Register counts from the FAA register of October 20, 2026.