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

SA3405WE

Installation of fuselage fuel tank in accordance with MR. RPM Top Drawing 57031, Revision E dated May 16, 1977, or later FAA approved revisions. Held by Rocky Top Leasing INC., which holds 7 approved modifications in all. Last revised November 7, 2008. System: fuel system.

What it applies to

Kind of product
Aircraft
Design holder
Twin Commander Aircraft Corporation; Twin Commander Aircraft Corporation; Twin Commander Aircraft Corporation
Models
560-F, 680, 680-F
Type certificates
2A4, 2A4, 2A4
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.