Modifications to a 182T
(FR: Modifier un avion certifié)
As it is certified, your aircraft cannot be modified freely. You have to make sure the modification will not alter the certification. We will review the main ways to do so.
- Modifications offered by the manufacturer
The manufacturer of the aircraft can release many modifications via Service Bulletin (SB), and when needed, Modification Kits (MK). Considering the Cessna 182T, I can think of addition of ADF, DME, TAS, Synthetic Vision, Chartview, WAAS capability, TAWS, stone LEDs… All by SB. It means that the manufacturer offers a path allowing the modification of the aircraft fully respecting its certification. When the modification requires new parts, a Modification Kit (MK) is also proposed, with all the needed parts numbers. The SB also specifies all the step to follow for the modification. The SB can be applied by a mechanics, without any further authorization. After application, the SB will be recorded in the aircraft logbook.
2. Existing Supplemental Type Certificates (STC)
Beside Service Bulletin, it is possible to modify a certified aircraft by following the STC route. Actually, equipment suppliers often undergo certification process for their products, so that final customers can install them on their aircraft legally. Usually, the certification process is undergone for several type of aircrafts, not just one type. When considering the application of an STC, it is very important to check that your aircraft is on the list, also called Approved Model List (AML). The STC is sometimes free, sometimes has to be bought. Whatever case, you have to get an Letter of Authorization (LoA) from the STC holder before proceeding to application. Then the STC will come with an installation manual to perform the installation by your usual mechanics. The catalog of available STC is very wide, considering FAA and EASA world (most FAA STC have equivalence as EASA STC), allowing many modifications to be applied to a certified aircraft.
At last, the STC will often come with an Aircraft Flight Manual Supplement (AFMS), and new Instructions for Continued Airworthiness (ICA) to be followed during maintenance. Sometimes, a Weight and Balance modification can also be provided.
3. CS-STAN: standard changes covered by EASA
Thanks to Part-ML, EASA has tried to simplify aircraft maintenance, changes and repairs. In that perspective, they have produced a list of Standard Changes and Repairs, also called CS-STAN. We are now relying on release #4, from April 2022. You can find a list of dozens of standard changes and repairs. That means, by respecting the conditions detailed for each CS-STAN, you can apply a modification to your certified aircraft legally. Each CS-STAN applied will be recorded in the aircraft logbook, an a Form123 filled and signed, by both the mechanics and owner. As simple as it goes.
4. Applying for EASA minor and major modifications
You may have special modifications in mind, that SB, STC and CS-STAN may not cover. In that case, you can apply for a specific modification approval directly by submitting to EASA. Depending on the complexity of the change, you will fall into Minor or Major modification. Those modifications request are usually submitted by workshop used to deal with EASA, not independent mechanics or owners. Technical details will be requested. The study by the EASA, in order to get approval, will be at the cost of the owner. Minor and Major mod can be considered like STC with limited applicability to just… one aircraft !
The different ways to modify your certified aircraft
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