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

SA98AL

Installation of two (2) Stoddard Aero Service Model 17 auxiliary fuel tanks in the PA-18A, PA-18S, PA-18-125, and PA-18-135 models and installation of two (2) model 18 and/or two (2) model 19 auxiliary fuel tanks in the -150 models. Fabrication and installation must be in accordance with Stoddard Aero Service Drawing List No. 98, dated February 7, 1975, or later Federal Aviation Administration approved revision. Stoddard Aero Service Airplane Flight Manual Supplement is required with -150 models having four (4) auxiliary tanks installed. Held by Cub Crafters INC, which holds 62 approved modifications in all. Last revised January 26, 2012. System: other and general.

What it applies to

Kind of product
Aircraft
Design holder
Piper Aircraft Inc.; Piper Aircraft Inc.; Piper Aircraft Inc.; Piper Aircraft Inc.; Piper Aircraft Inc.; Piper Aircraft Inc.; Piper Aircraft Inc.; Piper Aircraft Inc.; Piper Aircraft Inc.; Piper Aircraft Inc.; Piper Aircraft Inc.
Models
PA-18-125 (Army L-21A), PA-18-135, PA-18-150, PA-18A, PA-18A-135, PA-18A-150, PA-18AS-135, PA-18AS-150, PA-18S-125, PA-18S-135, PA-18S-150
Type certificates
1A2, 1A2, 1A2, 1A2, 1A2, 1A2, 1A2, 1A2, 1A2, 1A2, 1A2
On this site
Piper PA-18 Super Cub 3,620 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 22, 2026.