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

ST00623LA

Installation of gasket heater on flush/fill line lever lock valve assembly. Held by Transdigm, INC. Last revised May 5, 1998. System: engine.

What it applies to

Kind of product
Aircraft
Design holder
The Boeing Company; The Boeing Company; The Boeing Company; The Boeing Company; The Boeing Company
Models
737-500 Series, 737-400 Series, 737-300 Series, 737-200 Series, 737-100 Series
Type certificates
A16WE, A16WE, A16WE, A16WE, A16WE
On this site
Boeing 737 2,892 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 20, 2026.