Aircraft Modification

Providing high quality, cost-effective, enhancements

Aircraft modifications are changes made to the product’s initial type-design with the aim of improving or enhancing the aircraft’s capability according to the operator’s needs and/or regulatory requirements.


21jAeroDesign has extensive experience in installing and testing approved aircraft modifications. We’re holders of the supplemental type certificate (STC) for aircraft modification. This means we are able to make approved changes to an existing type of aircraft, engine or propeller.

21jAeroDesign’s scope of approval for aircraft modification covers:

  • Cabin interiors
  • Cargo compartments
  • External schemes, placards and markings
  • Flight deck interiors
  • Nacelles (air intake, fan cowls, thrust reversers)
  • Hydro-mechanical systems

From seats to slats, lavatories to liveries, we provide high quality modifications according to your specific requirements.

Modifications we have approved include:

  • Zero passenger seat passenger cabin configuration STC (A320FAM)
  • New EPA CFM56-5 adapter ring outer flange segments
  • New EPA key tool for CFM56-5 and V2500 fan cowl (lockable) forward latch
  • Installation of a Low Frequency Underwater Locating Device (LF-ULD)
  • Introduction of fast setting aerodynamic sealing for flight compartment windows
  • New EPA cabin floor panels
  • New EPA cargo compartment floor panels
  • New EPA cargo compartment sidewall and partition panels
  • Interior placards
  • Modifications to galleys, lavatories, partitions and bulkheads
  • Safety and emergency equipment installation
  • Miscellaneous cabin equipment installation
  • Interior decorative laminates and paint finishes
  • Changes to the Layout of Passenger Accommodation (LOPA)
  • Seat covers
  • Floor coverings
  • Emergency escape path marking
  • External paint schemes and liveries
  • External decals and markings

Here are some examples of modifications designed by 21jAeroDesign:

ATA 25 – Equipment/Furnishings


The Installation of a Low Frequency Underwater Locating Device (LF-ULD)


CAT.IDE.A.285(f) (COMMISION REGULATION (EU) 2015/2338) makes installation of a underwater locating device operating at a frequency of 8,8 kHz ± 1 kHz mandatory by the 01 Jan 2019, unless the aircraft is operated over routes on which it is at no point more than 180 NM from the shore.


The LF-ULD is a self-powered, fully self-contained device. It operates immediately after emersion in fresh or sea water omitting an electronic pulsing signal. The purpose of the LF-ULD is to assist search and rescue teams in locating aircraft wreckage undersea.


Over 150 installations of this modification have been completed, each one taking around 4 hours. Two brackets are installed on the aircraft structure onto which a composite adapter panel is attached, the LF-ULD is then mounted to the adaptor panel. A placard is installed on the outer face of the cargo lining panel to identify location of the LF-ULD.

ATA 25 – Equipment/Furnishings
A320FAM Zero Passenger Seat Cabin Configuration

A320FAM Zero-Passenger Seat Cabin Configuration

This 21jAeroDesign Supplemental Type Certificate (STC) approves a zero-passenger seat cabin configuration, whereby all passenger seats are removed. The STC provides an aircraft configuration that can be operated with minimum flight crew and without an amendment to the Aircraft Flight Manual (AFM).