SA09153AC-D
Installation of S-TEC System 55/55X Two Axis Automatic Flight Guidance System, Model ST-616. Held by S-Tec Corporation, which holds 1,083 approved modifications in all. Last revised October 12, 2001. System: other and general.
What it applies to
- Kind of product
- Aircraft
- Design holder
- Cessna Aircraft Company; Cessna Aircraft Company; Cessna Aircraft Company; Cessna Aircraft Company
- Models
- FR172E, FR172F, FR172G, FR172H
- Type certificates
- A18EU, A18EU, A18EU, A18EU
- 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.