SA09123AC-D
Installation of S-TEC System 55 Two Axis Automatic Flight Guidance System, Model ST-607, with Optional Autotrim System. Limited to Piper models PA-23-250 and PA-E23-250, s/n 27-2000 through s/n 27-7554172. Eligible on same models when equipped with approved turbocharged engines (250 hp) and/or wing tip tanks per STC SA1480WE. Held by S-Tec Corporation, which holds 1,083 approved modifications in all. Last revised August 29, 2007. System: engine.
What it applies to
- Kind of product
- Aircraft
- Design holder
- The New Piper Aircraft Inc.; The New Piper Aircraft Inc.; The New Piper Aircraft Inc.
- Models
- PA-23-235, PA-23-250 (Navy UO-1), PA-E23-250
- Type certificates
- 1A10, 1A10, 1A10
- On this site
- Piper PA-23 Apache and Aztec 1,316 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 5, 2026.