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

SA2726SW

Installation of 6-pole rotary squat switches. Held by Sierra Industries, INC, which holds 164 approved modifications in all. Last revised December 1, 1999. System: other and general.

What it applies to

Kind of product
Aircraft
Design holder
Learjet Inc.; Learjet Inc.; Learjet Inc.; Learjet Inc.; Learjet Inc.; Learjet Inc.; Learjet Inc.; Learjet Inc.; Learjet Inc.; Learjet Inc.; Learjet Inc.; Learjet Inc.; Learjet Inc.; Learjet Inc.; Learjet Inc.; Learjet Inc.; Learjet Inc.
Models
23, 24, 24A, 24B-A, 24B, 24C, 24D-A, 24D, 24E, 24F-A, 24F, 25, 25A, 25B, 25C, 25D, 25F
Type certificates
A5CE, A10CE, A10CE, A10CE, A10CE, A10CE, A10CE, A10CE, A10CE, A10CE, A10CE, A10CE, A10CE, A10CE, A10CE, A10CE, A10CE
On this site
Learjet 23 6 registered
Learjet 24 16 registered
Learjet 25 23 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.