Unicom

October 2005 Issue




Unicom: 10/05

How To Fly Twins
While the idea of ignoring the throttles and instead grasping the propeller levers on takeoff is intriguing, such a habit may be the wrong thing to do. While it is assumed that an aircraft is at full power during takeoff, it is important to note that not all aircraft use “full power” on departure. Therefore, it is wise for pilots to continue to push up the power to squeeze as much power out of the remaining engine as possible, resulting in a superior climb rate.

Another reason to test one’s selection of which engine to secure by retarding the throttle is that this action provides one extra layer of safety, one extra hoop through which pilots must jump, to prevent inadvertent feathering. I can only imagine the overzealous pilot (or multi-engine student) immediately feathering the wrong engine.

Finally, while the article states that pilots will save five to 10 seconds by using the “hands-on-props” technique, I have never seen it take a pilot such an eternity to identify and verify an engine when they are caught off guard, i.e., when faced with a very realistic simulated failure.

David Ison
Via e-mail

----------

More Safer Turbines
I read the “Are Turbines Safer?” article in the June 2005 issue and was tempted to comment on it at that time but didn’t get around to it. In your August issue the three letters related to the same article revived my interest in the subject. Mine is from the standpoint of a pilot-owner of a small single Jet Prop.

I flew it 1297 hours during a seven-year ownership. The airplane was a Beechcraft A-36 with an Allison 250 B-17 C turbine (now called Rolls Royce). The STC turbine conversion is done by Tradewind Turbines of Amarillo, Texas. To begin, it is easier to fly, with fewer engine adjustments to be made than an IO-520. Read: no mixture or propeller adjustments. Also important is the greatly reduced vibration factor and a 10-decibel quieter cockpit. And, of course, greatly improved performance is a joy. It is more reliable and it is typical for these engines to make it to hot section inspection and TBO intervals without significant maintenance. When maintenance is required, it almost always is routine. That was not my experience with pistons. My last IO-520 reman needed new pistons after 300 hours. Continental furnished the new pistons at no charge, but the labor was on me and the airplane was grounded for a month.

It is encouraging that progress is being made in cost reduction in the manufacture of small turbines. When substantially lower acquisition costs are the norm, it will be no contest against pistons.

Flying the turbine has been a great experience for me and has spoiled me for flying a piston.

Howard C. Turnley
Via e-mail


Few of our recent articles have generated as much reader mail as this one. To recap, one point the article’s author tried to make is that—all other things being equal— the turbine engine’s reliability may not enhance aviation safety. He based this point on the concept that one reason piston singles are not considered all-weather airplanes is the risk that the lone engine could fail at an inopportune time, leaving one with few or no choices for a “safe” emergency landing.

Many readers took issue with this concept, basically pointing out the turbine’s inherent reliability, the lower number of moving parts, and the safety and dispatch records achieved both by the military and scheduled airlines. Those are all good points.

But until and unless the rest of a single-engine airplane’s systems catch up to the quality and redundancy of Transport category aircraft, there will always be instances when the realities of risk management dictate that we really shouldn’t be flying a single, no matter what powerplant it uses. If we fly a turbine single like it’s a 757, we may be asking for trouble.

----------

Losing The Race
Regarding “Racing Weather” (Accident Recap, August 2005), it was a fascinating and timely report, especially considering the recent Air France accident in Toronto.

David Breznick
Via e-mail


Thanks, David. I hope it won’t surprise you to learn that I’ve “been there, done that” before. In addition to the obvious dangers of deliberately putting one’s airplane and passengers in the path of violent weather, the very real chance of distraction—like forgetting to lower the gear or misconfiguring the airplane in the event of a go-around—raises its ugly head in this scenario.

I’ve learned the hard way that it’s best to find some clear air, or a good-weather bolt hole, and wait out the bad stuff. There’s an old cliché floating around about how it’s better to “be on the ground, wishing you were in the air.”

----------

Maintaining Balance
I enjoyed the article on Fuel Management (“Got Gas,” July 2005) by Ray Leis. He suggests, “to keep the weight equally balanced,” fly one hour on a side then switch every hour after that.

While that is a reasonable and common practice, I suggest a slight modification: Make the first tank switch after a half hour, and then go to the hourly switch after that. This accomplishes two things. First, the weight of one side over another stays within a “half hour” of each other, rather than the one-hour gap that occurs with Mr. Leis’ method. Second, I find it easier to remember to switch the tanks earlier in the flight. Depending on the flight and the conditions, this half-hour “checklist item” keeps me mentally sharp and sets the tone for the remainder of the flight. Thanks again for a great article!

Marc Epner
Via e-mail


Good points all, especially if one is burning fuel from a tip tank or if the tanks’ design distributes fuel along the wing’s span instead of its chord.

Personally, I burn from one side for the first hour, then two hours from the other side, then I go back to switching tanks each hour. The airplane never really gets wing-heavy, I minimize wear and tear on the fuel selector—I nominally have eight hours of gas when the tips and mains are full—and it’s easier for me to do things on the hour, rather than every 30 minutes.

To me, the key is adopting a routine with which you’re comfortable and sticking to it. If you perform some significant task like switching tanks—or changing your engine’s oil—the same way each time, there is less chance for a mistake to creep into the routine.

----------

More On Maule?
I read Aviation Safety religiously and find it very informative. One thing I have noticed, however, is the lack of discussion (pro or con) on Maules. I am considering buying a Maule and would like some discussion of any rants or raves—so far everything I’ve read about it is great.

Denne Howard
Via e-mail


When we look at a specific aircraft’s safety, it’s usually because there’s something that needs attention—like the article on the Tomahawk’s spin characteristics in this issue. If you’re looking at a tailwheel-equipped Maule, we’re not aware of any show-stoppers, other than the tailwheel.

Maules are utilitarian airplanes with excellent runway performance but are short-coupled, which can lead to unintentional groundloops if the pilot can’t keep the tail pointed backward. If you’re looking for an all-metal airplane, you may want to keep looking: Maules are still tube-and-fabric.

Your best bet for detailed analyses of the Maule and similar aircraft would be our sister publication, Aviation Consumer. Check out the magazine’s Web site <www.aviationconsumer.com> for subscription info and the complete text of any previous articles on the Maule models.