Letters: 04/04

Diesel Notes
Thank you for the article on the Maule with the SMA diesel engine. (See Aviation Consumer, October, 2003.) I found it was a fair assessment of the installation. If I may, Id like to bring an update and clarify a few points:

The engine produces 230 HP in ISA condition at sea level. Its power decreases progressively from SL to 5000 feet, where it stabilizes at 200 HP to about 10,000 feet.In other words,the engine produces 230 HP at SL, 215 HP at2500 feet and 200 HP at 5000 feet, all smoothlycontrolled through the computer.

The engine is no longer limited to five minutes at max takeoff power (230 HP) so one can cruise above the beach at 1000 feet at 224 HPcontinuous, for example.Thismeans you only touch the throttle once tofull forward position to take off and leave it in place forfast cruise, whatever the selected altitude.

The engine ceiling will be increased to 18,000 feet by mid-2004, therefore increasing the ceilingof the Maule to that same altitude.

Since your flight, throttle response (we dont have a throttle per se on the engine, so we call it a power lever) has been adjusted and is smooth, with no spikes.

Fuel consumption:to our surprise,you are not the first one to question fuel consumption. I suppose GA is so used to high fuel consumption with the gasoline engines that our low numbers are difficult to believe.

However, the numbers printedin our engine operating manual are true. Wedid not lie to the authorities that certified the engine! Our fuel specific consumption is .35 BSFC and varies very little with horsepower output as opposed to a gasoline engine.

Overhaul cost: your figure of $22,500 dollars is higher than we expect. Our goal is $15,000, which further decreases the operating cost of our engine.

Some items that are included in our engine as opposed to the IO-540are theElectronic Engine Controland turbocharger. A similarly equipped IO-540 might very well be more expensive than our engine.

You might have mistaken our STC upgradekit price for the Cessna 182at $77,000 for a list price, which includes not only the engine, but also engine mount, cowl, three-blade composite propeller, accessories, instruments, single power lever and manuals.

Installed weight is only about 60 to 70pounds heavier than the original Lycoming in an M-7-235, due mostly to the addition of the turbocharger.

-Thierry Saint Loup
Customer Support


Venturi Back-Up?
With reference to your back-up article in the December, 2003 issue, why dont you ask Gramps about a Super Venturi as a vacuum back-up. Aircraft Spruce will sell you one for $57.65.

They will power both gyros and never wear out. They will ice but so will your airframe and you dont have a back-up airframe. Drag? How much drag would a venturi produce compared to a landing gear, wing strut, rotating beacon and so forth?

-Arthur Thompson
via e-mail

As we noted in the article, we think venturis are a good back-up idea. Theyre relatively cheap and reliable but will freeze. Were actually more concerned about legal approvals for installing venturis in aircraft that werent certified with them. Given the FAAs foot-dragging on field approvals, this could be more of a headache than its worth.


More on PFDs
In your article on the Garmin G1000 in the Feburary, 2004 issue, you said: There are mechanical issues, too. Maybe youve noticed that all of the PFD-equipped airplanes have side controllers or sticks, not a yoke that emerges from the panel right where the PFD needs to be.

The new Cessna 182 and 206 now have side controllers? Just keeping you honest.By the way, great article on the C340. Ive hada 1979 model since 1998 and its a great personal airplane.

And RAM still sells both the VI along with the VII 335 HP upgrades. Major difference is larger size of the intercooler on the VII which allows it to produce the same 335 HP at 38 inches MP/2700 RPM as the VI does at 41 inches MP/2700 RPM. RAM has great support of a terrific product.

I have 203 gallons of fuel capacity, Keith air conditioning, known ice, simple pressurization, VGs, speed brakes, lots of avionics(CNX80, MX20, WSI AV-200, WX-500, SL30, GTX-330, Argus 7000CE, King KI-825 EHSI, RDR 2000VP, Bendix/King 200 AP/FD) 1830 pounds of useful and the airplane is still faster than theCessna 414.

My wife used to put up with trips in other GA airplanes but preferred the airlines. She now hates going commercial.

-Rich Clark
via e-mail

Youre correct. As we go to press, Mooney has announced that it will equip its airplanes with the Garmin G1000. Those aircraft dont have side controllers, either. That said, both companies will still have to do some engineering to accommodate the large screens.


iPOD and Altitude
As Jeff Hurst suggested in his letter in the February, 2004 issue, tablet PCs and many other computing devices are limited in operation to 10,000-feet MSL.

The critical components are the disk drives. Theyre not airtight and they depend upon aerodynamic lift to keep the heads flying above the magnetic surfaces. Disk drives operate at constant RPMs, so the amount of lift generated by the heads in thinning air is reduced with altitude.

I learned about this when trying to use my Apple iPod to feed the intercom in my turbonormalized Bonanza. Climbing through 16,000 feet, the iPod became erratic then stopped working altogether.

It worked okay after landing, but you cant count on this. Contact between the heads and disk surfaces will eventually damage both.

-Doug Kaye
Kentfield, California


WSI Datalink
I read Ian Blair Fries recent article on his WSI datalink travails with great interest. (See Aviation Consumer, February, 2004). We installed the same product in our Cessna 210 a few months ago.

We have two Garmin GNS430s, but have heard and seen such bad results with their Echo Flight-based datalink that we opted to go for the portable WSI set-up. Id like to offer the other side to Fries nightmare story.

We had absolutely no trouble with the FSDO during our installation. As long as the AV-100 receiver was not permanently installed in the aircraft (its Velcro-mounted under the rear seat), the FAA viewed it as portable. It was a breeze.

We also had none of Fries problems with computer set-up. I have to believe thats because, in contrast to Fries, we purchased the FG-3600 tablet PC from ADR Electronics.

This came as a bundled package, already set up as an Electronic Flight Bag and ready for WSI and Jeppesen software. We had no installation problems and didnt spend any time on computer set-up.

All in all, were thrilled with the WSI product. Compared to the Echo Flight and Bendix/King products (which we have experience with), we have found this system to be extremely reliable, easy to use and packed with the best weather data available.

-John Zimmerman
via e-mail


Rapco Rejoinder
I read the letter from the president of Rapco and he doesnt seem to like having his product criticized. (Aviation Consumer, January 2004.) Good.

I noticed he didnt state why his product was better than the competition though, other than saying Rapco checks vane wear. I want the inside skinny on why one product is better than another, relative to cost, and if the vested-interest producer has a problem with that and doesnt have a problem with their inferior product, well, I want to know that, too.

These product reviews sometimes have the distinction of being opinion and I only, stress only, want non-biased (non-manufacturers) opinions. Thanks for giving me that through your magazine.

-Bruce Williams
Whitehorse, Yukon Territory