Changing the prop on an EASA aircraft
 

Hi All,

Yes, it's me again!

I have been considering ways of increasing the cruise speed on my 77 Archer II. It has the stock 60" prop on it and indicates the book figure of around 105kts at 75% power. It only has the basic spats so doesn't go much faster. All Archers post 77 have 62" props and full wheel fairings and of course are well known to cruise around ten knots or more faster.

The opportunity to change to a reconditioned 62" prop has come up and I am wondering what the legalities are surrounding the change. In simple terms any change to the basic design and configuration needs an EASA STC to be issued. Trouble is only those post 2003 are listed on their web site so I have no way of knowing if this has been done before. The FAA STC list also shows no previous entries on the subject.

Mention has been made that the change may be accommodated on the Archer 'type certificate' but I can't find anything that relates to pitch, only what the maximum RPM may be. In any event making the change without including the full fairings would create a hybrid configuration that the POH would not provide performance graphs for so I don't see the FAA or EASA wearing that.

Has anyone done this on an EASA aircraft and if so how did you go about it?

Any help appreciated.

BB

Not again....

Possible alternative.

Might be easier (cheaper?) than putting the 62" prop on.

Welcome to MT-Propeller

Their main headquarters is on your side of the pond and EASA friendly.

I helped several people install these props for similar reasons and haven't heard anything negative.

Worth an email or call. Might be able to help get around the full fairing issue to get your speed??

Good luck!
W1

Thanks Wrench. (And thanks for your help on the corrosion problem last summer. It all got painted out)

The composite prop is certainly worth a thought. I will check the price although I suspect it will not be cheap.

The FAA type certificate simply states that I must have a 76" Sensenich 76EM8S5 rotating within a 100RPM limit in ISA conditions. It makes no mention of what the pitch should be. Is the inference that I can change to a 62" pitch so long as I remain within the RPM limits?

BB:

Yes, but…

Since the TCDS doesn’t differentiate between the -0-60 and -0-62 versions you can use that “62” prop on your plane. But you could also adjust your “60” prop toward a “62”.

You might gain better cruise, but you’ll lose a bit of climb also. It is what it is.

The Archer IIs are all under the same TC model variant. Basically the "same" plane.

So while you could physically tweak your ’77 model toward a ’78 model, you’ll be hindered by RPM limits and performance charts for your serial number aircraft. Ironically, TCDS Note 11 and 24 allows a ’78 model owner to remove his spinner and some fairings effectively slowing the aircraft down to a ’77 model speed.

Maybe look for a STC’d Fairing Kit that has a supplement allowing the use of the ’78 Archer limitations??

Maybe post on the US Piper Owners forum for some input?
http://www.piperowner.org/forum/forums.html

Contact Piper itself. Maybe they have a Service Bulletin or Letter that provides a means to get the ’78 model performance out of a ’77 model???
http://www.piper.com/

Then again… you can always upgrade to an Aero L-39 for improved cruise performance….

W1

PS: I was told there is a possible Hartzell STC prop option for a PA-28. Cheaper than MT??

If it has been done under an AAN pre EASA then it can be done without a MOD under grandfather rights, ( unless things have changed ) I have done a quick scan through the UK AAN's but cannot see it, it also allows any MOD done by any other Country in EASA as an AAN. I seem to recall some people wanting to fit a prop on some big twin in the Bristol area and the CAA rejecting it until the people found it had been done previously in Italy or the likes and then they had to allow it.

https://www.caa.co.uk/Commercial-ind...pproval-notes/