SA4-1197
Control lock, locking rudder, elevator, and ailerons. Held by Avcomp LLC, which holds 9 approved modifications in all. Last revised November 8, 2025. System: flight controls.
What it applies to
- Kind of product
- Aircraft
- Design holder
- The Boeing Company; The Boeing Company
- Models
- 75 (Army PT-13), A75 (Army PT-13A; -13B; -13C)
- Type certificates
- A-743, A-743
- On this site
- Boeing 75 18 registered
Boeing A75 Stearman Kaydet 979 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 7, 2026.