SA09285AC-D
Installation of S-TEC System 20/30 Single and Two Axis Automatic Flight Guidance Systems, Model ST-727-20/30, according to Bulletin No. 827, Revision 6, dated 1-21-11 and Master Drawing List No. 921029, Revision F, dated 1-21-11 or later FAA Approved revisions of the above data (28 Volt System). Held by S-Tec Corporation, which holds 1,083 approved modifications in all. Last revised February 24, 2011. System: other and general.
What it applies to
- Kind of product
- Aircraft
- Design holder
- Piper Aircraft Inc.; Piper Aircraft Inc.; Piper Aircraft Inc.; Piper Aircraft Inc.
- Models
- PA-31, PA-31-300, PA-31-325, PA-31-350
- Type certificates
- A20SO, A20SO, A20SO, A20SO
- On this site
- Piper PA-31 Navajo and Chieftain 935 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.