Letters: 01/08

Hate Mail?

You stated in the October issue that “…with the exception of Beech and Cessna, buying a new airplane is still a crapshoot.”

So tell us how many death threats have you received from Piper marketing people and new owners of Piper aircraft?

Dick Grant
Via e-mail

None, actually. While conceding that were guilty of some hyperbole, its also worth noting that of all the long-established light aircraft manufacturers, only Beech and Cessna havent been through bankruptcy cycles.

Neither has Diamond nor Cirrus, but both are Johnny-come-latelys compared to Beech and Cessna, which between them, have remained profitable for more than 100 years. Aircraft manufacturing has always been cyclical. The trick is

weathering the downturns, which Cessna and Beech have.

War of Winds

In your “WSIs New Datalink: Lots of Display Choices” in the December 2007 issue, you said, “As datalink technology has matured, we find that pilots are still interested in a select core group of weather products which include NEXRAD, winds aloft, METARS, TAFs and perhaps lightning.

While the other products might be gravy, most owners can do without them, saving $20 per month.” Winds aloft is not part of the basic product of either WxWorx or WSI. If you want the winds aloft product, then you have to spend the extra $20 per month.

Richard Korn
Via e-mail

CamGuard Comments

I wanted to respond to the letter you received about CamGuard. (See November 2007 Aviation Consumer, Letters.) I read the letter from Mr. Simon and would like to comment on the situation. Let me say I agree with you about the autogas as the cause of the deposits in this engine. I offered to analyze the deposits for Mr. Simon.

As a bit of background: When I was with Exxon, we found that 99 percent of deposits in aircraft engines come from the raw and partially reacted fuel from blow-by entering the crankcase. An engine that burns 10 gallons per hour can put 0.2 gallons of this highly unstable mix into the oil per hour. Most of it goes out the breather and it is not a problem.

However, the remaining fuel components oxidize into deposit precursors and form the resinous varnish that sticks to the internals of the engine. Lead particles in the oil, from leaded fuel, are captured in this varnish, adding thickness to the deposits.

On the hottest surfaces, valve guides and pistons, this varnish oxidizes further into hard carbon deposits. Dispersants and the base oil are responsible for suspending these deposit precursors, not the lead, but are easily overwhelmed as can be seen by looking inside any engine with more than 100 hours on it.

Autogas is inherently and purposely much less stable than avgas. Autogas contains 15 to 20 percent olefins, which are unstable double bonds containing molecules used to raise octane. Olefins are responsible for the gum forming tendencies, the copious intake valve deposits (cars), short shelf life and the bad smell of autogas.

In addition, the intake valve detergent additives in autogas, which cause combustion chamber deposits in cars, are particularly detrimental when they get in the oil. While avgas is stable for over a year, autogas will deteriorate in months. Adding these additional unstable fuel components and additives to the blow-by mix greatly increases the formation rate of deposits in the engine. In addition, the lead, from the alternate avgas use, may have contributed to the deposit thickness and the change over to the semi-synthetic oil could certainly exacerbate the problem. Think Mobil AV1.

The most common cause of exhaust valve seizure is carbon deposits between the valve stem and guide that build up over time. The cylinder with the smallest valve-to-guide clearance then becomes the first one to seize.

Accordingly, it is impossible to imagine how CamGuard could have significantly contributed to the deposits in the short time Mr. Simon indicated he used it. Data shows that the use of CamGuard quashes the deposit formation rate by preventing the formation of the deposit precursors.

Mr. Simon, by leaning his engine in flight, prevents much of this fuel/blow-by buildup, but he should also lean aggressively on the ground and any time the engine power is below 60 percent. CamGuard does not clean up existing deposits.

Mr. Simon has also told me his friends are using autogas and CamGuard. I would be very interested in their results as well.

Edward Kollin
Technical Director
Aircraft Specialties Lubricants

JPI Non-Response

With reference to your article on engine monitors (November 2007 Aviation Consumer) and JPI EZ Trends for Vista, I have an EDM 700 in my Bonanza. I used to use a Windows XP laptop for downloading and plotting engine data, but since upgrading to a new Vista-equipped laptop, I am unable to do so. JPI has been promising a Vista-compatible version for the better part of a year. At Oshkosh, their representative said a Beta version would be on their Website “any day now.” In the meantime, they have come out with a $200 memory stick arrangement. Im not sure why its so much.

When JPI made their software proprietary a few years ago, you guys did a great job of shining a light on it and forcing them to back down. Please look into when they are going to have a Vista version of EZ Trends available. What other download alternatives do I have? Thanks for your great publication.

Chris Fenger
Via e-mail

We have repeatedly queried JPI about this topic and other technical issues and they have repeatedly declined to respond. Bottom line? We don’t know where the company is with the Vista-compatible EZ Trends.