Letters: January 1999

Twin Costs
Rick Durdens article on owning a twin is a confirmation of my own experience. I operated a 1985 Saratoga SP for five years and my costs averaged $70 per hour. I was told that a twin would cost three times as much to operate. But, of course, I thought that was impossible.

I purchased a 1985 Seneca III two years ago and guess what? The average cost has been $195 per hour. Gas and oil cost is double and insurance and maintenance eat up the rest. I have had better luck than Durden in that my Seneca is an extremely reliable airplane. During the last 600 hours, I have only been delayed twice for mechanical problems.

Aside from the operating cost, I agree that a huge drawback to operating a twin is safety. Redundancy is great, but if I did not spend the time on quarterly training, I would not fly one. Anyone who considers a move to a twin needs to commit to regular single-engine training.

Why pay the price to go the same speed and carry the same load? I find the costs reasonable on every night flight, getting out of icing conditions or crossing the Rockies and Great Lakes.

Jim ODay
via e-mail

CermiNil Feedback
Thanks for the great article on CermiNil cylinders in the November issue of Aviation Consumer.

I bought my 1961 Beech Bonanza early last year. It had been we’ll maintained but had suffered a forgot-to-lower-the-gear landing and the owner decided to let it go instead of fixing it.

It was purchased by a Beech dealer, the prop was pulled and the engine was sent to T.W. Smith for overhaul with CermiNil cylinders. The dealer put it all back together and flew it for a month, then I bought it.

I had some misgivings about everything. T.W. Smith had a checkered reputation in my local area; some good reports, some bad reports. Also, no one had tried CermiNil around here.

However, after 216 hours, I no longer have any doubts about the engine or cylinders. An engine job can only be as good as the person who works on it. My engine had a loose accessory cover, which leaked due to sloppy mechanical work. But other than that, it has performed beautifully.

My engine has consistently used one quart of oil every nine to 10 hours. I change oil every 25 hours (Phillips XC 20W-50), run around 55 to 65 percent power and the engine seems very happy. It runs as smooth as a sewing machine, the compressions are fine and I can only hope that it continues like this.

My wife is very happy to fly with me now because the big Continentals are the smoothest engines weve ever heard.

And thus far, I have nothing but good news to report about CermiNil and T.W. Smith. I am very sorry to hear that he is closing up his shop.

Ron King
Laurel, Maryland

Encoder Additions
In his article on encoders in the December, 1998 issue, Gary Picou speaks from experience. Here are a few additional comments, based on nearly a decade of dealing with pilots on the subject of altitude encoders.

If everything were perfect, encoders would switch to the next 100 foot altitude at the 50-foot point. For example, as you climb from 6000 feet, it would switch to 6100 at 6050 feet and would switch to 6200 at 6150 feet. But nothing is perfect and barometric pressure is rarely 29.92 inches. In the real world, referring to the altimeter with local baro set properly, the encoder can switch to the next 100-foot increment at any point. A good encoder will switch at about the same point within each 100 feet, but as soon as you reset the baro pressure, the switching point (as seen on the altimeter) will change. Each 0.01 inch makes about a 10-foot difference.

Five minute warm-up time is about normal, depending on how cold the airplane was to begin with. Weve seen encoders take as much as 15 minutes. During that time, the encoder output is inhibited. From the controllers point of view, if your encoder is inhibited, you don’t have Mode-C at all.

Inside Class B airspace, this could result in a violation and there is no way for the pilot to see if his/her encoder has come alive yet.

Interestingly, the TSO requires an indicator to tell the pilot that the encoder is alive, but no encoder has such an indicator, nor do they have any provision for a remote indicator. The old AR-500 is the exception to the above. It puts out wrong altitudes during warm-up.

It doesnt matter if you have one of the fancy encoders that output altitude in 10-foot steps, the controller can only read your altitude in 100-foot jumps anyway. Worse yet, with a cockpit readout in 10-foot steps, the pilot cant see where the 100-foot jump occurs.

Encoding altimeters and blind encoders put out the same pressure altitude. Turning the Kollsman knob on an encoding altimeter does not change what the controller sees.

In some areas, the controllers no longer have benefit of using the same local baro correction that the pilot is given.

At the new SoCal facility, for example, five regions were combined into one and that entire facility is limited to a single barometric setting. Presumably, the same thing will happen as other facilities combine.

This can lead to altitude busts in situations where the pilot and his equipment are both performing correctly. There are many similar gotchas in the Mode-C system. If aviation attorneys would bone up on the technology, they could win some cases they are losing today.

Finally, and perhaps most important, if you are installing an altitude alerter that takes its data from the encoder, be sure the installer hooks it to the same encoder that the transponder is using.

Many installers have chosen to put in a second encoder because its cheaper and quicker than the labor involved in splicing into the existing wiring, which is usually buried and undocumented.

But the point of the altitude readout is to see the same data the controller is seeing. The installer must understand that this wont happen if the transponder and the pilot are looking at different encoders.

This is not a concern with AirSport alerters, they receive and display what the transponder is actually putting out.Garys article was great. I hope these points reinforce some areas where pilots might have misconceptions.

Darryl Phillips
AirSport Corporation

More on Multi-Vis
Just finished reading the oil article in the December issue of Aviation Consumer. I had just started to research the oil issue so I would be ready to break in and operate the factory reman O-470 I ordered this past Monday for my Cessna 182.

The sidebar on Continental jugs caught my attention. While trying to decide on a factory reman or field overhaul, I came to the conclusion that Continental had fixed their quality control problems and that new jugs coming out of the factory were holding up pretty well. Does this reconcile with your discussions with other owner /operators?

In the last paragraph of the article, Greg Travis says to stay away from multi-weight oil if you have Continental jugs built between 1990 and 1998. Is 1998 correct? If so, is he saying you should never run a big-bore Continental with straight-weight oil? Thanks once again for a timely article.

Mike Scaduto
via e-mail

We think the jury is still out on whether Continental has corrected the pre-mature cylinder wear problem.

Worth noting is that not every large-displacement TCM engine assembled with post-1990 cylinders suffered early cylinder demise. But weve certainly heard from many owners whose cylinders were junk at 400 hours.

Whether thats related to oil type is beyond us. As the article noted, the evidence is purely anecdotal. For new cylinders, we still think multi-viscosity oils are the better choice, all things considered.

GAMIjector Results
Your article on GAMIjectors in the November issue was interesting. Here are some additional comments. A good rule of thumb is that if fuel flows are within 0.6 GPH at peak EGT, GAMIjectors probably wont do anything (noticeable) for the engine. GAMI will tell you this.

For those who do not have an appropriate engine monitor, a good rule of thumb is that if the engine runs smooth lean of peak (as determined by a single probe), chances are that GAMIjectors will not do much. Of course there are exceptions to every rule, but based on our experience with IO-360-A1A and A3B6D engines in our Mooneys, we discovered long ago that these engines ran quite we’ll lean of peak. In our 201, we found that the engine ran much cooler on the lean side.

Having made this discovery and having researched the issue carefully, we installed an engine monitor and consistently ran these engines lean of peak, typically burning as little as 8.4 GPH at 10,000 to 12,000 feet. In the 201, this usually gave us 153 to 155 knots TAS.

We had no engine problems (never a bolt turned) with either engine and the -A3B6D went to 2004 TSOH (3044 TTSN, we got it at 1700+) before removal for conversion to a Missile.

We immediately discovered that temperatures were no issue with this engine. It runs very cool in cruise but we could not lean even to peak without the engine running rough, a sure sign that cylinders are not contributing equal power.

This TCM IO-550-A4B was equipped with TCM D-2 injectors. Installation of GAMIjectors immediately solved the problem of poor fuel distribution. Fuel flows which varied by 1.3 GPH at peak-or as close as we could get-now vary by as little as 0.3 GPH.

Leaning beyond peak is no problem. The hottest cylinder (and first to peak) with the TCM injectors was number 2. GAMIjectors changed this to number 5, closely followed by number 4. They work for us. GAMIjectors were created to solve a particular problem with Continentals. They work great in most cases we have heard about in IO-520s and IO-550s, provided the engines suffer from the typical symptoms of uneven fuel distribution.

We have heard less enthusiastic responses from owners of turbocharged TCMs. Based on our experience with two Lycoming IO-360s, we cant see that GAMIjectors would have helped us in either case.

Do GAMIjectors save fuel? If one chooses to run lean of peak, there is a fuel savings. If one chooses not to reduce fuel flow then there will be little or no savings. Our average fuel flow for 642 hours on the IO-550 is 13.96 GPH. Running lean of peak (at 65 to 67 percent power) results in fuel flows as low as 11.4 GPH. On a recent non-stop return from West Lafayette, Indiana, we burned 11.9 GPH for the 3:15 trip. Running rich of peak, the fuel burn is up to 15.5 GPH (assuming a minimum altitude of 4000 feet). On average, running lean of peak reduces fuel burn by approximately 1.5 GPH in cruise.

Naturally, there is some speed sacrificed running on the lean side. Typically, we find this to be 3 to 7 knots. This parallels our experience with the Lycoming engines.

Our suggestion is that anyone with an IO-360 (or any other engine) test the engine according to GAMI recommendations before spending money on something they might not need. Our experience with pilots indicates that once the money is spent, some will find a way to justify the purchase. As a result, there are favorable reviews for almost any after market product sold.

We think The Aviation Consumer can bring some balance to the issue by being more objective than the average private pilot with the lightened wallet. Keep up the good work.

Rae Willis
via e-mail

For the record, the turbocharged TCM owners weve spoken to report good results with GAMIjectors.