Approved modifications · supplemental type certificate · current · reissued

SA20GL

Installation of Woodward Type II electronic propeller synchronizer or synchrophaser system. (G-44A MODIFIED COLEMILL - STC 2-13) (500-A modified - Colemill STC SA340SO). Held by Ontic Engineering and Manufacturing INC., which holds 59 approved modifications in all. Last revised April 30, 2007. System: propeller.

What it applies to

Kind of product: Aircraft
Design holder: B-N Group Ltd.; B-N Group Ltd.; B-N Group Ltd.; B-N Group Ltd.; B-N Group Ltd.; B-N Group Ltd.; B-N Group Ltd.; B-N Group Ltd.; B-N Group Ltd.; B-N Group Ltd.; B-N Group Ltd.; British Aerospace (Scotland); The Cessna Aircraft Company; The Cessna Aircraft Company; The Cessna Aircraft Company; The Cessna Aircraft Company; The Cessna Aircraft Company; The Cessna Aircraft Company; The Cessna Aircraft Company; The Cessna Aircraft Company; The Cessna Aircraft Company; The Cessna Aircraft Company; The Cessna Aircraft Company; The Cessna Aircraft Company; The Cessna Aircraft Company; The Cessna Aircraft Company; The Cessna Aircraft Company; The Cessna Aircraft Company; The Cessna Aircraft Company; The Cessna Aircraft Company; The Cessna Aircraft Company; The Cessna Aircraft Company; The Cessna Aircraft Company; The Cessna Aircraft Company; The Cessna Aircraft Company; The Cessna Aircraft Company; The Cessna Aircraft Company; The Cessna Aircraft Company; The Cessna Aircraft Company; The Cessna Aircraft Company; The Cessna Aircraft Company; The Cessna Aircraft Company; The Cessna Aircraft Company; The Cessna Aircraft Company; The Cessna Aircraft Company; The Cessna Aircraft Company; The Cessna Aircraft Company; The Cessna Aircraft Company; The Cessna Aircraft Company; The Cessna Aircraft Company; The Cessna Aircraft Company; The Cessna Aircraft Company; The Cessna Aircraft Company; The Cessna Aircraft Company; The Cessna Aircraft Company; The Cessna Aircraft Company; The Cessna Aircraft Company; The Cessna Aircraft Company; The Cessna Aircraft Company; The Cessna Aircraft Company; The Cessna Aircraft Company; The Cessna Aircraft Company; The Cessna Aircraft Company; The Cessna Aircraft Company; The Cessna Aircraft Company; The Cessna Aircraft Company; The Cessna Aircraft Company; The Cessna Aircraft Company; The Cessna Aircraft Company; The Cessna Aircraft Company; The Cessna Aircraft Company; The Cessna Aircraft Company; The Cessna Aircraft Company; Gulfstream Aerospace Corporation; Gulfstream Aerospace Corporation; Partenavia Costruzioni Aeronauticas S.p.A.; Partenavia Costruzioni Aeronauticas S.p.A.; Partenavia Costruzioni Aeronauticas S.p.A.; The New Piper Aircraft Inc.; The New Piper Aircraft Inc.; The New Piper Aircraft Inc.; The New Piper Aircraft Inc.; Reims Aviation S.A.; Reims Aviation S.A.; Reims Aviation S.A.; Reims Aviation S.A.; Reims Aviation S.A.; Reims Aviation S.A.; Twin Commander Aircraft Corporation; Twin Commander Aircraft Corporation; Twin Commander Aircraft Corporation; Twin Commander Aircraft Corporation; Twin Commander Aircraft Corporation
Models: BN-2, BN-2A, BN-2A-2, BN-2A-20, BN-2A-21, BN-2A-26, BN-2A-27, BN-2A-3, BN-2A-6, BN-2A-8, BN-2A-9, B.206 Series 2, T310Q, 310Q, T310R, 310C, 310L, 310K, 310J, 310H, 310F, 310N, 310D, 310I, 310B, 310A (USAF U-3A), T310P, 310, 310E (USAF U-3B), 310G, 310P, 320A, 320B, 320C, 320D, 320E, 320F, 320, 340A, 340, 404, 336, T337H, 337H, T337G, 337G, P337H, T337F, 337F, 337, 337B, T337B, 337C, 337E, T337E, T337C, 337D, T337D, 402A, 402B, 402, 401B, 401A, 401, 402C, 411, 411A, 414, 414A, 421A, 421B, 421C, 421, G-44A, G-44 Series, P68C, P68C-TC, P68 TC "Observer", PA-23-250, PA-E23-250, PA-42,...
Type certificates: A17EU, A17EU, A17EU, A17EU, A17EU, A17EU, A17EU, A17EU, A17EU, A17EU, A17EU, A11EU, 3A10, 3A10, 3A10, 3A10, 3A10, 3A10, 3A10, 3A10, 3A10, 3A10, 3A10, 3A10, 3A10, 3A10, 3A10, 3A10, 3A10, 3A10, 3A10, 3A25, 3A25, 3A25, 3A25, 3A25, 3A25, 3A25, 3A25, 3A25, A25CE, A2CE, A6CE, A6CE, A6CE, A6CE, A6CE, A6CE, A6CE, A6CE, A6CE, A6CE, A6CE, A6CE, A6CE, A6CE, A6CE, A6CE, A7CE, A7CE, A7CE, A7CE, A7CE, A7CE, A7CE, A7CE, A7CE, A7CE, A7CE, A7CE, A7CE, A7CE, A7CE, A-734, A-734, A31EU, A31EU, A31EU, 1A10, 1A10, A23SO, A7SO, A23EU, A23EU, A23EU, A23EU, A23EU, A23EU, 6A1, 6A1, 6A1, 6A1, A12SW
On this site: Britten-Norman BN-2 54 registered
Cessna 310 1,410 registered
Cessna 320 137 registered
Cessna 336 35 registered
Cessna 337 Skymaster 370 registered
Cessna 340 707 registered
Cessna 401 51 registered
Cessna 402 174 registered
Cessna 404 26 registered
Cessna 411 10 registered
Cessna 414 Chancellor 605 registered
Cessna 421 Golden Eagle 769 registered
Cessna 500 Citation I 62 registered
Cessna P337 33 registered
Cessna T-310 207 registered
Cessna T337 193 registered
Partenavia S.P.A. P 68 16 registered
Pilatus Britten-Norman Ltd. BN-2 13 registered
Piper PA-23 Apache and Aztec 1,316 registered
Piper PA-34 Seneca 996 registered
Piper PA-42 59 registered
Vulcanair Spa P68 10 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.