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

SA503GL

Installation of wiring changes to aircraft equipped with dual flight directors to prevent the uncoupled flight director system trim control switch (TCS) from disrupting the coupled flight director/autopilot operation. Held by Gulfstream Aerospace Corporation, which holds 1,861 approved modifications in all. Last revised February 6, 1981. System: flight controls.

What it applies to

Kind of product
Aircraft
Design holder
The Cessna Aircraft Company; The Cessna Aircraft Company
Models
500, 550
Type certificates
A22CE, A22CE
On this site
Cessna 500 Citation I 62 registered
Cessna 550 Citation II 500 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 21, 2026.