Letters 07/98

Engine Monitors
Great article on engine monitors in the May issue. I decided to get a JPI EDM-700 with fuel flow based on my own limited research. I have a few quibbles with the product and your article, but basically think its the best available for the price on todays market. I have it mounted in the hole occupied by my old EGT location-which is now a nice paperweight-in my 1977 Skylane with an O-470U.

The reset button is inaccessible from the front and requires removal of the instrument or part of the panel for setting certain one-time-only parameters-alarm limits, carbureted or fuel injected, total fuel capacity, etc.

I don’t like the automatic mode, especially the way the instrument automatically reverts to auto mode after 15 minutes. This is non-programmable. Its possible to program the unit to omit items in the autoscan but I have to do it every time I turn the thing on.

There should be more than two buttons for operation and they should be bigger with a deeper action. Perhaps there could be a third button which toggled between auto and manual scan. The autoscan should only contain the EGT/CHT data and fuel flow. The alarms should take care of the rest. Instead, you have to watch the thing display its entire repertoire over and over again.

I like the lean find mode and use it often. I cruise at 65 percent power and lean to peak EGT. I wish I could just leave the unit in a configuration with cylinder temp and fuel flow side by side. But once you are out of lean find mode, thats not an option.

-Peter Ver Lee
via e-mail

I own three airplanes with three different monitors installed. I disagree with the opinion expressed that the leaning aid is not a great feature. That was the main reason I bought one. I use it on every flight.

The other reason to have one is knowing whats going on in all cylinders any time I want to see-such as over large bodies of water or mountainous terrain when your brain makes you think you heard something funny with the engine.

My Cessna 210 has a Masten Analyzer. Masten, of course, is out of business, but back in 1992, it had the most features, including fuel flow. Digital readout only, but thats fine because the display beeps and flashes if anything is out of limits.

I would buy that model again if they were still available. Push two buttons and begin leaning normally. The display flashes when the first cylinder peaks. Couldnt be simpler and you don’t need to stare at the instrument.

My Skybolt (experimental) has the Allegro. This unit works great too and also has fuel flow. Price is incredibly low. Leaning is equally simple and works the same way. Your chart on page 7 incorrectly says there is no lean find.

In any case, this one is heartily recommended. I wish they would STC it. Their span mode shows the temp difference between the hottest and coldest CHT and EGT. An incredibly convenient feature that gives a better indication than a bar graph picture. The units display is not as flashy as the others, since its an LCD display. But its very readable and all the info is there.

My Staggerwing has the JPI. This aircraft is not flying yet, but the instrument is installed and working. Looks to be a great instrument, too. I chose it because it was the only one to offer a nine-cylinder model. The bar graphs are neat, but the digital readout gives the real data. I would not want an instrument without the numbers, too.

One caution on the installation: The mounting screws must not be longer than 1/8 inch past the panel thickness. And their mounting hole is chamfered some so there isn’t much grip to the screws. Longer screws will crack the display glass. I did it twice. JPI allows you to pay for your mistake ($150), although their design causes this to happen as much as installer stupidity.

-Peter van Schoonhoven
Battle Ground, Washington

Progressives: Give em a Chance
With reference to Mr. Dykhouses comments on progressive lenses in your May issue. Obviously he had an unusual experience. Ive never had bifocals. I transitioned from plain glasses to progressives. I know of one person who had trouble with progressives and went to bifocals. But he was like Mr. Dykhouse and went from no glasses directly to progressives.

I found that progressives do indeed distort your vision but only for a day or two. My friends describe it as I do, as a barrel effect. The edges of your vision seem to pull up so it looks like you are walking in a large barrel.

Then that wonderful computer, the human brain, adjusts. Now, everything is normal and flying with progressives is wonderful. I cannot imagine flying could be as easy with bifocals.

Mr. Dykhouses lenses may have been ground or fitted into the frames incorrectly. I had a pair of progressives fitted into the frames so that the prescription started changing too high in the lens. I could have crisp distant vision only by tipping my head down and looking out the top of the lenses.

I knew it wasnt the prescription because the sunglasses were fine. They ground a new set of lenses and cut them to fit my frames so that the change started about half way down. I have used them for three years with no problems.

As far as not needing to adjust to them, you will always have an adjustment period when you change prescriptions. To think otherwise is a dream.

My friends who have had laser kerototomy to correct vision problems are finding the adjustment period to be one to three months, depending upon the change and the procedure used. Mr. Dykhouse is the exception and not the rule.

-Bernie Fehringer
Sidney, Nebraska

Firefly Retort
I read with interest everything that is written on the T3A trainers. (See Aviation Consumer February, 1998.) When you take a good airplane and stuff a much bigger engine on the front of it, you are going to have problems.

I had a flying club in England with the Slingsby T67A, a wooden Firefly, as a mainstay. In my opinion, this was an excellent basic aerobatic trainer. For a couple of months, I operated T67M 160 G-BKTZ. This was the first production model of the military spec airplane fitted with the 160HP Lycoming.

In this configuration, the glass composite airplane was nicely balanced. With 25/25 selected, all normal aerobatic maneuvers were able to be flown. After rolling to the inverted, lowering the nose was required for the entry to the outside loop and that was the only maneuver requiring a little bit of a dive.

The snags with the T67M were its poor aileron response inherited from its Fournier RF6B forebear. In the vertical for a stall turn-hammerhead to you-I rode the right rudder pedal without my foot on the left pedal. When I switched feet, my left foot slid right to the end of the tunnel because the left pedal came unlatched. I toed it round the stall turn! Those adjustable pedals were dangerous, in my opinion.

The highest licensed airfield in England is Dunkeswell at 850 feet and the temperature seldom reaches 80 degrees, thus I appreciate that hot and high here does not mean the same as it does in the U.S. Even so, I suspect that the 200 HP Firefly would have suited the USAF better. In the RAF, they tried to replace the 145 HP Gipsy-engined Chipmunk with the 200 HP Lycoming-powered Bulldog. But the Chipmunk was just so much better at weeding out new recruits that it replaced the Bulldog again.

The Americans always think more power is better and this is true if it is an awful airplane like a Pitts S2A. I have flown the Jungmann with the 105 HP Hirth, 125 Tigre, 150 Tigre and 150 Lycoming APM. Of all of these, the sweetest was the original Hirth-powered version. The Lycoming engine totally ruined the knife edge handling and the overall balance of this beautiful airplane.

Modifying an airplane originally designed for 160 HP into a monster with 260 HP does not work. Buy the airplane which was designed from the outset for that engine.

The Cessna 172 is a bus, forget it. I love the Mooney, its a great cruising airplane, but it isn’t an aerobatic aeroplane. You want something like an SF260. I bet a sexy airplane will attract more recruits as well.

-Michael Peare
Vancouver, British Columbia