The U.S. aircraft register, updated daily
Approved modifications · supplemental type certificate · current · issued

SA91SO

Modification of rotating field element G.E. 291C777G1 of G.E. 400 cycle alternator 2CM211A1. Held by Peninsular Armature Works INC., which holds 2 approved modifications in all. Last revised January 1, 1960. System: electrical power.

What it applies to

Kind of product
Aircraft
Design holder
General Dynamics Corporation
Models
22
Type certificate
4A27
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 21, 2026.