SA547SO
Installation of Bendix M-4D auto- matic flight control system in- cluding optional manual electric trim and optional flight director system in serial numbers 402B0301 and up, 4140351 and up, and421B0301 and up. Held by Bendix Corporation Avionics Div, which holds 102 approved modifications in all. Last revised August 17, 1973. System: flight controls.
What it applies to
- Kind of product
- Aircraft
- Design holder
- The Cessna Aircraft Company; The Cessna Aircraft Company; The Cessna Aircraft Company
- Models
- 421B, 402B, 414
- Type certificates
- A7CE, A7CE, A7CE
- On this site
- Cessna 402 174 registered
Cessna 414 Chancellor 605 registered
Cessna 421 Golden Eagle 769 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 22, 2026.