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Fuel systems

STC SA4-683

FAA DRS lists SA4-683 as Current · Reissued, held by Atlantic Coast Sea Planes LLC, for Grumman American Aviation G-21 and Grumman American Aviation G-21A. Recorded change: Installation of auxiliary fuel tanks in outboard wing sections. Snapshot dated June 30, 2026.

FAA-listed holder
Atlantic Coast Sea Planes LLC
Aircraft configurations
2
FAA revision date
FAA status
Current · Reissued

Recorded modification

What the FAA record covers

Installation of auxiliary fuel tanks in outboard wing sections.

SA4-683 identifies the approval, recorded holder, named aircraft, and modification scope. It does not confirm kit availability, serial-number effectivity, data rights, price, or installation authority.

Applicability

Aircraft named in FAA DRS

Named aircraft: Grumman American Aviation G-21 and Grumman American Aviation G-21A. Confirm the approved model list, serial effectivity, configuration, and certificate revision.

Grumman American Aviation G-21654Grumman American Aviation G-21A654

Buyer checks

Confirm before sourcing

  1. 01Does it cover the exact Grumman American Aviation G-21 and Grumman American Aviation G-21A model, serial range, and configuration?
  2. 02Which tanks, plumbing, usable-fuel assumptions, and inspections apply?
  3. 03Who can legally supply the design data, kit, instructions, and ICAs?
  4. 04What parts, labor, conformity, and return-to-service work are excluded?

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