Letters: 06/08

Tire Trouble

In your tire test article in the April 2008 issue, you say “Were going to stick with comparing tread depth, wear rates and price to determine the best value.” That sounds fine, but when I look at your overall value ranking, your conclusions do not seem to agree with your data.

Based on your stated criteria for measuring value, the Condor is the most cost effective or best and the Flight Custom III is the least. I fly a Mooney M20J and

Airplane Tire Test

make about 100 landings per year. My tires (Condor or Michelin Aviator) usually last about four or five years. So, it seems like the max landings are overstated by a factor of 10.

Boyd Wilson,
Via e-mail

Thanks for the very thorough tire evaluation. You didnt give a clue, other than reference to trailer weight, as to how the tire-pavement contact pressure was maintained and at what level. Can you equate it to an approximate aircraft weight or do you consider it a minor factor compared to forward speed?.

Did you actually inflate to 30 PSI? My 600 x 6s take 55 PSI. It should make a difference in wear pattern/profile.

Dick Lewis,
Madeira Beach, Florida

Several readers wrote to make the same point-hey, you guys got this backwards. And they would be right except for one detail: We biased the test inversely to favor tread depth. As explained in the article, the leading cause of tire trashing is flat spotting due to landing with brakes on, or hard, locked-wheel braking or out-of-balance wheels that tend to force the tire to touch down at the same point on its circumference each time.

While our findings do show that mid-priced tires like the Condor will deliver more landing per dollar than a tire costing three times as much, its shallower starting tread presents a weakness. Our tests also showed that tires with deeper tread will survive one or more wheel locks while the mid-priced products with lesser tread wont. Add up the labor of changing the cheaper tire twice or even three times and youre better off with the more expensive tire in the first place. One reader noted that the equation is different for taildragger pilots, who learn not to lock wheels as a matter of survival. For these airplanes, the mid-priced tires are probably the better choice, since they need less protection against flat spotting due to locked wheels.

As for tire pressure, we used the equivalent of a light trainer, which typically requires 24 to 32 PSI. Weight on the rig also simulated trainer loading. We think-but cant prove-that wear directionality would be similar at higher weights, although the wear rate would be greater.

Credit Where Due

When everything clicks to keep our planes flying, it is usually a team effort and the team deserves a round of applause. While flying down to our winter home in Lakeland, in hard IMC, the transponder in our Arrow tanked. Andy Solomon at Columbia Air Service had the plane towed over to MAC Avionics on immediate request, despite heavy Sun n Fun demands. Within a day, Don Ruhl, at MAC had bench tested the transponder and found it not receiving. It would need to go to Narco, for no telling how long.

My logs were locked up in Virginia and I recalled the transponder being just over a year old. I talked to Rick Wiseman of American Avionics, at Sun n Fun. He suggested a call to Ralph Keepers back at the shop in Seattle, who was kind enough to e-mail me a copy of the sales invoice for the unit.

As it turned out the purchase was just 11 months before. Off the transponder went to Narco, where Laura, Tom and the rest of their team repaired it under warranty in only one day, with no special plea on my part. That must at least equal the record for the best ever service in avionics! I am impressed that all these folks are so professional at helping us enjoy the gift of flight.

Stanley D. Rasberry,
Lakeland, Florida

Zaon Correction

Reference your article on the Garmin 496 and Control Vision Anywhere Map in the May issue, you’ll probably get a lot of similar letters in response to this article. Your writer apparently is unaware that you can, in fact, connect a Zaon XRX to a Garmin GPSmap 496 or 396.

I have a Zaon XRX connected to a Garmin 396 using a special cable provided by Zaon. The 496 can also be connected this way. I get traffic from the XRX displayed in TIS format on the 396 map. Its fantastic and far superior to the Zaon built-in display.

John Kearney,
Via e-mail

Our writer has duly had his fingers broken in the service of journalistic accuracy, but as the hammer descended, he said “Hey, I didnt write the caption.”

Clark Complaint

As a devoted David Clark headset user, I thought the X11 would be the best of the best. I have had DC headsets for over 30 years and currently have four. After using the new headset, I determined it was defective. I simply couldnt understand the controllers. It seemed as if the voices in the earpieces were out of sync.

I returned it to David Clark and they changed the left headset and the headset controller. That brought an improvement. Then I read your first evaluation of the headset and I agree it isn’t as good as previous Clark headsets. It has weak and muddy audio.

I have since returned to my DC H10-13X. It may not have the comfort of the X11, but I can hear the controllers clearly. My X11 is in the back, in the bag for the passengers if they want one. We have a Bose in the co-pilot seat of our MU-2. I have used it off and on and agree its very good. I think Clark needs to redo the circuitry and put more soundproofing in the X11.

Kenneth Earl,
Germantown, Tennessee

How Ya Figure That?

Would you please explain the ingredients that go into the “Typical Retail” prices that you give in the eighth column of the Cessna 206 Select Model History table on page 27 of the May 2008 issue of The Aviation Consumer?

For example, are these numbers supposed to represent actual final sales prices versus asking (advertised) prices? What in the way of equipment is assumed, especially radios and autopilots? Also, what do you assume for aircraft and engine times and apparent overall condition?

I thought the article was well-written and is generally in good agreement with my 17 1/2 years experience of owning a 1965 P206.

Charles Crume,
Oak Ridge, Tennessee

We use the typical retail values given in the Aircraft Bluebook Digest. These are themselves based on surveys of actual sales prices, but could include data from many sales or just a few. These prices assume mid-time engines and include adds and subtracts for various equipment, which are listed in the price section.