Good evening,
I own a Mooney M20J (EASA registered) and it's current MTOW is 1243kg. My father is a freelance Part 66 mechanic, so we are doing our own maintenance on the aircraft (50h/100h/annual inspection).
The engine is going to reach it's calendar TBO (12 years / but less than 400h TT) soon. In France, the only way to run the engine beyond the calendar TBO is to visit a Part M/F or a Part 145 shop ($/€ and possibly poor work quality...) in order to perform some tests (engine health check, corrosion check...) every year.
For the Mooney M20J, these tests are -ALREADY- performed during the regular annual inspection but the rules are strict : The engine tests have to be performed YET another time by an EASA approved maintenance organisation every year.
However the rules says that for ELA1 aircraft (MTOW under 1200 kg), these engine health tests can be performed by a freelance Part 66 mechanic (ie My father during the regular annual inspection).
During the last airwothiness review, the airwothiness inspector said "no exception will be made even for some Cessna's with a 1207kg MTOW.
I'm actually very interested to decrease the aircraft MTOW to 1200 kg in order to meet the ELA1 requirements.
Since I fly with 2 POB most of the time this won't affect any of my flyings.
Does someone know what's the right path to decrease the MTOW to 1200kg ? Do I need to contact an EASA Part 21 company in order to submit a Major mod or STC to EASA ?
When I see the proposal #2 of the EASA NPA 2012-17 , I'm sure that I will be able to reduce my maintenance costs if I meet the ELA1 category (I would be done with spending 4k€ every 6 years to overhaul a prop in a very good shape...)
Reducing the certified MTOW is a change to the Flight Manual (the POH) and is definitely a Major Modification, under both FAA and EASA regimes.
I am not aware of anybody having succeeded in doing it initially in Europe.
It was done on the N-reg Seneca (to bring it below 2000kg) quite a few years ago as an STC (and EASA accepts that; not sure of the details).
It was, I am told, also done for the N-reg Meridian (but EASA reportedly does not accept that one).
Do I need to contact an EASA Part 21 company in order to submit a Major mod or STC to EASA ?
I think that is the preferred procedure 
After all, EASA was created primarily to provide economic support to EASA Part 21 companies 
Your other option is to go N-reg. Under current laws/proposals you will need both FAA and EASA pilot papers but the maintenance regime is much more sensible (generally; not always).
Make it 1199kg, that can save you some landing fees
I think that is the preferred procedure.
After all, EASA was created primarily to provide economic support to EASA Part 21 companies
Any recommandations of serious Part 21 companies ?
I talked to the CAA about this a couple of years ago - I have an Annex II vintage aeroplane with 1013kg MTOW and we perceived that we could save money on airport and insurance costs by getting MTOW below the tonne.
CAA were quite happy to do it. It would require a major mod and STC, with an associated POH amendment. They were happy for me to do it myself, but I am a design signatory with a couple of approved companies so they might not be so generally user friendly.
We didn't actually get around to it, but that was for completely unrelated reasons.
I've also done it with a few PtF aeroplanes for professional purposes. I've not tried it with an EASA aeroplane, but it's not a difficult technical problem.
G
Thank you for your reply. I will try to find a suitable Part 21 company (still looking for recommendations btw)
Going N-reg is not option for me since we have an EASA Part 66 licence and not the "FAA A&P".
You could also switch to another EASA reg where it's easier to have a custom maintenance program and ignore the TBO. In Germany it is easy to get (although no longer free of charge) and I know of several French aircraft owners that are on D-reg.
I don't have any direct personal experience of an EASA 21 company.
Well, I know of two, who I used to generate some documentation when I was on G-reg, but both abandoned the project because they got stuck and I had agreed a fixed budget
I am sure there is a list on the EASA website somewhere, and if you start with one that's local to you...
The best thing with all matters concerning aircraft and component certification is to meet with the "authority" face to face, because there are usually at least two different approaches, all but one of which will not be offered in writing
