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

ST00877LA

Installation of Litton LTR-97 Fiber Optic Gyro systems. Held by Northrop Grumman Systems Corporation, which holds 62 approved modifications in all. Last revised February 22, 2016. System: other and general.

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; The Boeing Company; The Boeing Company; The Boeing Company; The Boeing Company; The Boeing Company; The Boeing Company; The Boeing Company; The Boeing Company; The Boeing Company; The Boeing Company; The Boeing Company; The Boeing Company; The Boeing Company; The Boeing Company; The Boeing Company; The Boeing Company; The Boeing Company
Models
DC-9-11, DC-9-12, DC-9-13, DC-9-14, DC-9-15, DC-9-15F, DC-9-21, DC-9-31, DC-9-32 (VC-9C), DC-9-32, DC-9-32F (C-9A), DC-9-32F (C-9B), DC-9-32F, DC-9-33F, DC-9-34, DC-9-34F, DC-9-41, DC-9-51, DC-9-81 (MD-81), DC-9-82 (MD-82), DC-9-83 (MD-83), DC-9-87 (MD-87)
Type certificates
A6WE, A6WE, A6WE, A6WE, A6WE, A6WE, A6WE, A6WE, A6WE, A6WE, A6WE, A6WE, A6WE, A6WE, A6WE, A6WE, A6WE, A6WE, A6WE, A6WE, A6WE, A6WE
On this site
Douglas DC-9 7 registered
Mcdonnell Douglas DC-9 93 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 7, 2026.