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

SA1237NW

Installation of two PA-18, 17 gallon wing fuel tanks, one header tank. Held by Bellows, Paul. Last revised May 21, 1981. System: airframe structure.

What it applies to

Kind of product
Aircraft
Design holder
Piper Aircraft Inc.
Models
J3C-65 (Army L-4; L-4A; L-4B (Navy NE-1); L-4H; L-4J (Navy NE-2))
Type certificate
A-691
On this site
Piper J-3 Cub 3,804 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.