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

SA4891NM

Installation of Honeywell Vertical Speed Indicator/Traffic Resolution Advisory (VSI/TRA) display. Held by Acss (Aviation Communication and Surveillance Syst, which holds 33 approved modifications in all. Last revised February 28, 2002. System: instruments and avionics.

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
Models
727C Series, 727-100 Series, 727, 727-200F Series, 727-100C Series, 727-200 Series
Type certificates
A3WE, A3WE, A3WE, A3WE, A3WE, A3WE
On this site
Boeing 727 37 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.