Sting Owners: Billet is Your Mechanical Fuel Pump Now!

[drdehave]

Two of us in our group of five Sting Sport owners switched to the "new" Rotax mechanical fuel pump during the past 6 months. Both of our cases (hold the presses: a third "bad case" has now surfaced) resulted in "bad" outcomes. For us, that new Rotax pump produced fuel pressures all over the map--often exceeding upper/lower pressure limits and triggering warning lights in the cockpit!

Recently, following up on all this "pump misery" one of the two owners decided to look at the current Master Equipment list for TL Ultralight airplanes to see what it said about fuel pumps. And what did it say? It said that, as of September 31, 2011, for TL-Ultralight, TL-2000, Sting, TL-3000 Sirius (all models/all SNs), the approved mechanical fuel pump is now the Billet Pump (series). Read it here http://www.sting.aero/owners/
(click "Documents" then "Master Equipment List."

Fortunately, I had already switched out the "new" Rotax pump in favor of my old one--and it is still running perfectly like a top! But, it is good to know that next time a new mechanical fuel pump may be indicated, the Billet can be installed. My experience suggests that the "new" Rotax pump is not ready for prime time in certain TL Ultralight configurations. I wonder if TL's engineers reached a similar conclusion?

Thank you Michael! It pays to visit your airplane builder's website occasionally, huh?

[roger lee]

Rotax did have some of the first pumps with high pressures. They built a very expensive test stand to check all that comes into the US from the Bahamas. They are pretty much right at 4.5 psi now. What they did find is too many people with no recirculating lines (required), incorrect setups and running an electrical back up pump all the time. The electric pump will boost the pressure approximately 1 psi. So if you sender is off even .5 psi or more then you show a high reading. The big thing they found was how inaccurate the fuel pressure senders are in the low psi range that our systems operate at. The majority of the issues after the bad pumps were re-called were bad sending units. It is very common for a VDO sender to be .5- 1 psi off on most aircraft.

I talked to Billet a while back and they didn't have any pumps ready even though they had done a little testing. Using the Billet pump will void any warranty on you engine and any help from Rotax should you have a major engine issue. I can't believe Sting would take this liability on themselves.

[FastEddieB]

The majority of the issues after the bad pumps were re-called were bad sending units. It is very common for a VDO sender to be .5- 1 psi off on most aircraft.

The VDO sending unit on my Sky Arrow gradually showed less and less pressure. I bought a new one and relocated it off the engine in the hopes that less vibration might increase longevity.

I mention this because the VDO sender with the same part number as original was shipped with a warning label that said something like "NOT TO BE USED FOR FUEL APPLICATIONS". I always wondered the reason for the warning.

BTW, at about 260 hours and about five years my circa 2007 fuel pump is still going strong.

[drdehave]

Okay, Roger, let's say, for the moment, that I accept what appears to be your underlying thesis: that those new Rotax pumps are pretty much A-okay, now, and that the real culprits were/are the crappy installations, including inaccurate pressure senders, that they're put onto.

Then, why, on every older TL Ultralight installation, at least, that I know of, did the old, original Delco mechanical fuel pump perform flawlessly for hundreds of hours--never once indicating any out-of-bounds pressures (even when being "boosted" by the electric pump)--until they eventually wore out and died? Maybe they didn't know about the crappy installation they were on?

And why did the powers to be at TL trash-can the new-style Rotax pump for the Billet in their 2011 Master Equipment List?

Hummm... There seems to be more questions than answers here.

[roger lee]

I don't have an answer for you that would fit that aircraft Mfg.
912's have for the most part used the Pierberg or AC mechanical pumps. Where did Delco fit in? Why did TL change, who knows. It just puts all the liability on their shoulders and not Rotax. Most aircraft Mfg's won't do that. Right now As an aircraft Mfg TL is out there by themselves using this Billet pump. I have only heard of a few Experimental guys using it. It may be a good pump, but after talking to them there are darn few out there in use. It would be a risky proposition for an owner or Mfg to want to be a test subject.

[drdehave]

Sorry--a slight brain slip, there! I meant AC. I knew it was like a Chevrolet car--but I didn't want to go all the way out to the hangar to take a look!

My Sting and the ones I am familiar with, came with the AC mechanical fuel pump. For me, 850 hours later, it has never had one out-of-bounds pressure reading, whereas the "new" Rotax pump I had on for about 50 hours (the old one never failed; I just decided a new one might be a reasonable precaution) before depositing it in the dumpster behind my house, had red cockpit lights flashing out-of-bounds every flight.

I will say, it certainly did help keep us occupied in the flying "off season," though. Was it bad fuel? Was it vapour-lock? Was the sender working correctly? Was the sender fuel line gunked up? etc. etc.

Sorry, I hate to keep bad-mouthing this new pump by Rotax, but it's the way I (and now, three other Sting owners with identical experiences; there is clearly something going on here!) feel. You know, sort of like the strong opinions you get when you ask a rhetorical question such as: "What's the best oil to use?" or "How often should I change the oil?" etc. etc.

Having said all that, we have just heard that Billet pumps are out of stock and won't be available for 2 months! Geeze, I hope that old AC keeps chugging along like a top!

By the way: Anybody reading this who still has a new AC pump squirreled away someplace--or even a used one in good condition, I will give you a grocery bag-full of cash for it!