Changing the prop on an EASA aircraft
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Changing the prop on an EASA aircraft
Hi All,
I have long 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. 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
I have long 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. 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
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Boeing Boy, what is the exact designation of your PA-28? Have a look at the TCDS as applicable to your model. (TCDS 2A13),
http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgMakeModel.nsf/0/58e3800616d183568625805f00534b82/$FILE/2A13_Rev_56.pdf
it will tell you the maximum prop diameter. I'm seeing diameters from 72.5" to 82" depending upon the model of PA-28. From experience with EASA and noise compliance, I suggest that you will be too burdened to install a prop which exceeds the TCDS diameter for that model.
PM me if you need more detail.
http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgMakeModel.nsf/0/58e3800616d183568625805f00534b82/$FILE/2A13_Rev_56.pdf
it will tell you the maximum prop diameter. I'm seeing diameters from 72.5" to 82" depending upon the model of PA-28. From experience with EASA and noise compliance, I suggest that you will be too burdened to install a prop which exceeds the TCDS diameter for that model.
PM me if you need more detail.
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Thread Starter
Thanks Pilot DAR.
I had already found the type certificate on the FAA web site and it simply states that my aircraft must use a 76EM8S5 prop and it must be exactly 76" in diameter. It also specifies the maximum and minimum RPM in ISA conditions but makes no mention of what the pitch must be. The inference therefore is that so long as the new prop complies with the rev limits it can be either 60 or 62" pitch. However I find that strange since all the performance graphs in the operating handbook would no longer be accurate.
I had already found the type certificate on the FAA web site and it simply states that my aircraft must use a 76EM8S5 prop and it must be exactly 76" in diameter. It also specifies the maximum and minimum RPM in ISA conditions but makes no mention of what the pitch must be. The inference therefore is that so long as the new prop complies with the rev limits it can be either 60 or 62" pitch. However I find that strange since all the performance graphs in the operating handbook would no longer be accurate.
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Surely the pitch of the propellor is a function of the Sensenich Part number and the same part number applies to all serial numbers of the Archer 11 according to the TCDS. Where does the suggestion of a 62" pitch on later aircraft come from?
Ah - found the reference here: http://www.sensenich.com/files/docum...1349891787.pdf
The determination of what's currently allowed will be the IPC. I did a trawl of the UK CAA AAN database and couldn't see any existing approval for the suggested change.
Ah - found the reference here: http://www.sensenich.com/files/docum...1349891787.pdf
The determination of what's currently allowed will be the IPC. I did a trawl of the UK CAA AAN database and couldn't see any existing approval for the suggested change.
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The post 77 Archers all had 62" pitch props. The earlier ones had 60".
This is the entry from the FAA TCDS:
Propeller and Propeller Limits Sensenich 76EM8S5.
For S/N 28-7690001 through 28-7790607: Static r.p.m. at maximum permissible throttle setting, not over 2425 r.p.m., not under 2325 r.p.m. at sea level, ISA conditions. (Reference aircraft Maintenance Manual for test procedure to determine approved static r.p.m. under nonstandard conditions.) No additional tolerance permitted. Diameter: Not over or under 76".
For S/N 28-7890001 through 28-8690056; 28-8690061; 28-8690062; and 2890001 through 2890205: Static r.p.m. at maximum permissible throttle setting, not over 2340 r.p.m., not under 2240 r.p.m. at sea level, ISA conditions. (Reference aircraft Maintenance Manual for test procedure to determine approved static r.p.m. under nonstandard conditions.) No additional tolerance permitted. Diameter: Not over or under 76".
My aircraft is 7790402 so I am in the first category but as you can see there is no mention of what pitch the prop should be.
This is the entry from the FAA TCDS:
Propeller and Propeller Limits Sensenich 76EM8S5.
For S/N 28-7690001 through 28-7790607: Static r.p.m. at maximum permissible throttle setting, not over 2425 r.p.m., not under 2325 r.p.m. at sea level, ISA conditions. (Reference aircraft Maintenance Manual for test procedure to determine approved static r.p.m. under nonstandard conditions.) No additional tolerance permitted. Diameter: Not over or under 76".
For S/N 28-7890001 through 28-8690056; 28-8690061; 28-8690062; and 2890001 through 2890205: Static r.p.m. at maximum permissible throttle setting, not over 2340 r.p.m., not under 2240 r.p.m. at sea level, ISA conditions. (Reference aircraft Maintenance Manual for test procedure to determine approved static r.p.m. under nonstandard conditions.) No additional tolerance permitted. Diameter: Not over or under 76".
My aircraft is 7790402 so I am in the first category but as you can see there is no mention of what pitch the prop should be.
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Posts crossed. The Sensenich table in my last post shows the difference by year although not by aircraft serial number. Changing a prop requires an STC - expensive and time consuming but maybe someone elsewhere in European has done it before.
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ChickenHouse. You are right that in reality it's down to someone to sign it off but the problem is that without an STC or some other document supporting the change the risk will be that someone else in the aircraft's future may refuse to sign and ground it.
Looking at Wigglyamps graph it would appear my year (77) must be fitted with a 60" prop otherwise it needs an STC.
Thanks for replies.
Looking at Wigglyamps graph it would appear my year (77) must be fitted with a 60" prop otherwise it needs an STC.
Thanks for replies.
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@BB: Yes, and experience shows that the person signing off always have some special personal wishes, sometimes non-official sources of wisdom easing things as well, so I always advice to get the person on the task as soon as ever possible.
You don't have to buy a new prop as your existing prop can be re-pitched by a prop shop. They just put it in a fixture and bend it to the new pitch.
The issue as others have pointed out is getting it signed off. I don't see how you could make the max TCDS specified static thrust RPM limits with a repitched prop. It will likely be too course to make the necessary revs.
The issue as others have pointed out is getting it signed off. I don't see how you could make the max TCDS specified static thrust RPM limits with a repitched prop. It will likely be too course to make the necessary revs.
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I see you are looking to increase the speed of your Archer.
Do you,have a "knots2u" kit fitted?
I had one on my US registered Warrior and it gave about 10 knots better speed plus a lower stalling speed,a better rate of climb, and a better rate of roll.
When the aircraft was moved to the UK register there was no problem.
Do you,have a "knots2u" kit fitted?
I had one on my US registered Warrior and it gave about 10 knots better speed plus a lower stalling speed,a better rate of climb, and a better rate of roll.
When the aircraft was moved to the UK register there was no problem.
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Thanks 3Wheels.
The kit isn't fitted but I am looking at the idea. Another aircraft local to me had it fitted and utilised a German STC to get approval. I think the fact that you imported yours made it easier.
The kit isn't fitted but I am looking at the idea. Another aircraft local to me had it fitted and utilised a German STC to get approval. I think the fact that you imported yours made it easier.
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In these changing times is it not acceptable for an FAA STC to be accepted by EASA without all the gold plating that the UK CAA has previously deemed necessary?
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As it happens I am literally today organising buying a new prop for my 1975 Archer II currently nearing completion of a complete refurb at Ft Lauderdale Executive.
The prop is a 60" pitch too, the 62" came for later airplanes - mine is FAA registered, not sure if one can fit a 62" pitch prop on it i.e. that it has been STC'd - if anyone knows it had I would be interested to hear.
If upping the cruise is the objective, I agree - go for speed mods - I have none of mine but it is/was very well rigged and has flush fitting door, cowl etc. I could make 115kts at 75% and occasionally would get close to 120kts at various altitudes.
Was thinking of adding some to mine but the costs are already past US$100,000 (don't ask!) and almost three years so kind of given up on that - the prop came as a nasty surprise last weekend - seems it "lost" half an inch on its diameter somehow over the past twenty years
The prop is a 60" pitch too, the 62" came for later airplanes - mine is FAA registered, not sure if one can fit a 62" pitch prop on it i.e. that it has been STC'd - if anyone knows it had I would be interested to hear.
If upping the cruise is the objective, I agree - go for speed mods - I have none of mine but it is/was very well rigged and has flush fitting door, cowl etc. I could make 115kts at 75% and occasionally would get close to 120kts at various altitudes.
Was thinking of adding some to mine but the costs are already past US$100,000 (don't ask!) and almost three years so kind of given up on that - the prop came as a nasty surprise last weekend - seems it "lost" half an inch on its diameter somehow over the past twenty years
There is no free lunch. The 62 in prop will be a bit faster, + - 5 kts, but you will loose about 100 ft/min of climb rate
