View Full Version : Robinson R22 MOGAS STC in the UK?
25th Jun 2012, 18:25
I'm wondering if it's possible to get the MOGAS STC for the R22 here in the UK?
I've been reading about it and it seems available in the US and it has been mentioned on a few sites I've discovered:
copters.com » Other Stuff You May Find Useful During Preflight (http://www.cantrell.biz/copters/helicopter-aviation/helo_mech/r22-preflight/other-stuff-you-may-find-useful-during-preflight/)
(he states :
"You can only run automotive fuel in the Robinson if you have an STC for
the aircraft. You buy the STC, and keep the paperwork in the aircraft.
That gives you the right to put automotive fuel in that particular
aircraft, but not in others. In other words, if you have 5 R22s, you would
have to buy 5 copies of the STC if you wanted to use autogas in all of
Robinson R22 (with some comparisons to the R44) (http://philip.greenspun.com/flying/robinson-r22)
(he states :
"The R22 burns 100 low-lead Avgas. With an STC, it can be converted to run car gas, but this requires changing the carburetor float ball.")
And I've found it mentioned at least a dozen times on other websites/blogs written by instructors and operators.... however, they are all US based.
One supplier I found is here : Autogas STC (http://solaraero.org/autogas.htm)
Also, is this modification 'approved' by Robinson too? And Lycoming?
Does anybody in the UK have this MOGAS STC on their R22? Or can anybody point me in the right direction? Any good or bad experience to share?
Why? Cost savings really - 1 hour's worth of AVGAS can cost anywhere from £70 to £74, but with MOGAS, we're talking around £41 - £44 (based on 8.5 gallons per hour in a Beta II and current AVGAS prices and unleaded petrol at Shell/Esso)
Grateful for any advice. Thanks
26th Jun 2012, 08:03
Suggest you look in CAA CAP 747, Generic Concessions (2,3,4,5,6) as a starting point.
Some R22 engine combinations are listed.
26th Jun 2012, 12:00
What about a helicopter with fuel injection and the Lycoming engine.Can that be flown on MOGAS more easily ??
26th Jun 2012, 13:36
I suspect there would be very little sympathy for a MOGAS STC for anything in the UK at the moment, from our regulator.
Mogas is widely used in Rotax engines, and notably in those fitted to gyroplanes like the Rotorsport. There have a been number of recent problems, some reported and others not, that relate to vapour locks that have caused reduced power and other worrying things. The current view is that these are probably caused by extra volatile components introduced into modern petrol by the oil companies. There seem to be 2 principal culprits: ethyl alcohol (bioethanol) added to keep the green lobby happy, and butane added to make winter petrol a bit "spicier". It was the extra butane in "winter petrol" that caused the unexpected massive vapour cloud at the Buncefield fire that lead to the big explosion.
Following some incidents it is being recommended that Mogas is NOT used in Rotax engines above 20 Celsius in some types. This is a complete pain for Rotax owners. The Rotax engines do NOT like Avgas 100LL. They get bunged up and there are all sorts of extra maintenance requirements.The only option to be available is to use Avgas UL91. This is recently being sold by Total, but only at around a dozen outlets at present, which is not much use to most people.
I suspect that the CAA will shortly mandate the use of 91UL in pretty much everything Rotax that is G registered (but not an EASA aircraft).
That being the case, I doubt any new Mogas STCs for certified aircraft would stand much of a chance at the moment, but I may be wrong.
An STC for G-Reg would have to run the EASA gauntlet. I note that the Solar Aero STC is "EASA pending" :hmm:
I looked into this some time ago and from what I researched, which granted was more R44 than R22, the STC was NOT available for fuel injected engines. I don't remember anything about floats but perhaps thats just the 22. Basically I think a few seals had to be changed and that was about it. The vaporisation problem is one that I have heard of but I believe only a problem if there was slot of ethanol in the petrol. The engines themselves are dinosaurs and will burn anything ( avgas or mogas) it's just making sure it gets into it :)
Keep us all posted as with the price of avgas we all need a better solution......if there os one!
27th Jun 2012, 08:39
The plot thickens.
I found this CAA document: http://www.caa.co.uk/aandocs/27743/27743030000.pdf
AIRWORTHINESS APPROVAL NOTE NO: 27743 Issue 3
Due to the problems of obtaining Avgas in quantities suitable
for private operations from unlicensed aerodromes, the CAA has previously
allowed certain aircraft to use leaded motor gasoline conforming with BS:4040,
subject to certain conditions.
Supplies of BS:4040 are now restricted by environmental legislation. The purpose of this AAN is to validate the FAA-approval of unleaded motor gasoline in aircraft in order to facilitate the use of the fuel by private category aircraft in the UK.
This AAN is concerned with the approval of unleaded motor
gasoline for the aircraft only, and does not approve any engine to use
unleaded motor gasoline. The use of this fuel in aircraft engines is subject to
separate approval under AAN 27744.
Issue 2 of this AAN amends the approval for the Robinson R22
model to extend MOGAS use to those R22 models equipped with Lycoming O-320-B2C
or Lycoming O-360-J2A.
So, it appears the caa approve?? Unless I am reading it wrong?
27th Jun 2012, 11:51
Had a quick look and on the face of it, this does seem to link to the "Howard Fuller STC " for Robbos, the one from Aero Solar.
However, it does a have a temperature limitation of 20 Celsius in the conditions.
Before you spend money on the STC, I suggest you make sure by talking to your maintenance organisation +/or local CAA Surveyor.
28th Jun 2012, 11:02
I run an R44 Raven 2 so it won't apply to me.
However, as a fixed wing pilot also, I am aware of several engine failures attributed to fuel vapour lock. I remember a tragic accident at Woburn a few years back. Very hot day, vapour lock, both(?) died.
Unless there is compelling evidence that dismisses the risk of fuel vapour lock absolutely in an R22 I wouldn't dream of using Mogas.
It will otherwise be a trade off between cheaper fuel and a greater risk of ending up in a smoking hole.
Pay the money.
28th Jun 2012, 11:22
"it does a have a temperature limitation of 20 Celsius in the conditions"
Not likely to be much of a problem in Blighty :cool:
28th Jun 2012, 12:07
You need to be careful of vapour lock, especially in a helicopter. The freewheel clutch removes any flywheel effect from the driven elements if the donk were to cough. A restart from 1,000 ft would sure clean the tubes :\
Re: the 20 deg C limit, you may be able to get away with it in the UK most of the time, but if we ever got a summer, it leaves you in a pickle.
The cost saving is significant though.
28th Jun 2012, 12:53
This very topic came up this morning - I was speaking to an engineer at PDG about an R22 earlier as I wanted to know if the R22 could run on UL91 (which is now available at Barton and 20p a litre cheaper than AVGAS), but he didn't recommend it.
He was looking after a customers R22 that was running MOGAS a few years ago (with the STC) and it wrecked his engine valves. What cost savings he had with the MOGAS/AVGAS price difference was compleletely lost as the Engine needed a lot more maintenance and valve changes. He said that UL91 is literally just high octane MOGAS, so he didn't recommend it.
I wonder if Slones or Heliair have an 'official' view on using MOGAS / UL91??
28th Jun 2012, 14:27
I think you can pretty much guess what the manufacturers or their reps will say,(they will play it "safe") but it would be worth asking before you went down the mogas or UL91 route. If you really want to be safe (in a different way) ask your insurance company too.
Any change like this turns the aircraft into a quasi-experimental and you into a sort of test pilot. Engineering is built on experience: change things and things are different and more uncertain. Obviously the STC owner will have done some testing (sufficient to satisfy the FAA) but from what rf says it may not cover all the angles. It would be very interesting to know how much mogas flying with the R22s has taken place, and how many problems had really occurred.
Back when I was younger and foolisher I had sticky valves in my R22. The in-flight symptoms amounted to a semi-engine failure. R22s went through a phase with sticky valves back then, (mid 1990's) and I don't know whether anyone really found out why. I do recall that the problem was usually found on one cylinder: the one that had the worst supply of cooling air. Incidentally, when the engineers split the engine I could not believe how much lead had been deposited in the combustion chambers and exhaust outlets as a result of using 100LL. It was so much, it must have significantly changed the engine compression ratio.
Small changes can make big differences to engine performance. Removing lead will have some advantages but it may come with problems too, especially if the engine was never originally designed to use the new fuel.
I did a bit of a search and found that some people recommended the occasional tank of 100LL to keep some lead in the system. For an engine design that was created to use leaded fuel, that makes some sense to me.
Like most things in life the decision is a risk balance. Knowledge is the key.
29th Jun 2012, 00:07
To my knowledge this is the 'official line' taken from the Key Reprints, found at:
Key Reprints - Lycoming (http://www.lycoming.com/support/tips-advice/key-reprints/index.html)
''Lycoming does not permit the use of any fuel other than those specified in our latest edition of Service Instruction No. 1070. Although Supplemental Type Certificates (STC) now make the use of automotive fuel, which meets minimum specified standards, legal for use in some aircraft, reciprocating engine manufacturers and most major oil companies do not approve. While it is true that octane levels appear adequate, these organizations are of the opinion that the varying quality control standards applicable to automobile gasoline produce undue risk when it is used in aircraft. Several specific reasons are given for the non-approval of automobile fuel:
1. Its use reduces safety. Although an operator may find that the engine runs well on a specific grade of auto fuel, there is no assurance that fuel from the same tank will be of the same quality when purchased the next time. Risk is increased.
2. Its use can void warranty, or result in cancellation of the owner’s insurance.
3. The storage characteristics of automotive fuel are less desirable in comparison with the good storage characteristics of aviation gasoline. After several months, stored automotive fuel may suffer loss of octane rating, and tends to deteriorate into hard starting, along with forming gum deposits that cause sticking exhaust and intake valves, and fuel metering problems, resulting in rough running engines. The turnover of automotive fuel is so fast that long-lasting storage characteristics are not required.
4. The additives in automotive fuels are chemically different from those designed for aviation, and contain auxiliary scavengers which are very corrosive, and under continued use can lead to exhaust valve failures. They also cause rust and corrosion in the internal parts of the engine. The allowable additives for aviation gasoline are rigidly tested and controlled. There is no uniform control of additives in automotive gasoline. Many different additives are used, depending on the fuel manufacturer. For example, one fuel company adds a detergent to clean carburetors. This additive creates a significant increase in the affinity of the gasoline for water which can cause fuel filter icing problems in flight if outside temperatures are cold enough.
5. Automotive fuels have higher vapor pressures than aviation fuel. This can lead to vapor lock during flight because the fuel companies advise that automotive fuels can have double the vapor lock pressures of aviation gasoline, depending on the seasons of the year and the location because of climatic conditions. In addition, automotive fuel also increases the possibility of vapor lock on the ground with a warm engine on a hot day.
6. Although the fuel octane numbers shown on the pump of automotive and aircraft gasolines may be similar, the actual octane ratings are not comparable due to the different methods used to rate the two types of fuels. Furthermore, aviation gasolines have a lean and rich rating, i.e., 100/130, whereas motor gas is not tested for a rich rating.
7. Automotive fuel used in an aircraft engine may lead to destructive detonation or preignition and potential engine failure at high power conditions.
8. Please review the Mo-Gas fuel requirements in your state or destination.
SUMMARY:Auto fuel is now being used as a substitute for Grade 80 aviation gasoline under STCs issued by the FAA. Most major oil companies and engine manufacturers continue to recommend that aircraft piston engines be operated only on aviation gasoline. Deterioration of engine and fuel system parts have been reported in aircraft using auto fuel. Operators should consider the added risk of using auto fuel in aircraft. Remember — a pilot can’t pull over to the side of the road when fuel creates a problem with the engine.''
...anyone remember the trouble Tescos encountered a few years back? Infact, google 'Tesco fuel problems' and it auto suggests 2012, 2011, 2010....
Regardless of whether you decide to pay the '$750 STC' (I personally wouldn't even think about it), I would strongly suggest reading the Key Reprints cover to cover anyway, as it is brimmed full of info on your engines.
1st Jul 2012, 18:50
A big thank you to everybody that has replied about this MOGAS thing... after reading the lycoming information and having a chat with an engineer at a main dealer on Friday, it seems that it is definitely NOT recommended, despite what the STC holder claims.
And it's a shame about UL91 not being recommended too - two fingers up to the environment then :-(
max roll rate
1st Jul 2012, 19:18
i think the engeneer that says its high octaine mogas is wrong .
it is infact Avgas with out the lead injected so has none of the
mogas problems . if you read the latest service instruction from
Lycoming the engine in the R22 Beta is approved and if the engine
is approved EASA i belive approve the airframe.
we have been running engines on UL91 in our planks for 6 months
no problems but an improved fuel burn in some O-360 types
here is a link to the lycoming service instruction .
Regards Chris Brown AD manager Turweston