Letters 10/99

Pathetic Indeed
Your article in the June Aviation Consumer on retractable step-ups was very interesting and informative. However, I must take issue with Paul Berges description of the Rockwell 112 Commander performance as pathetic.

Most 112 owners report speeds in the 128 to 133 knot cruise range at 10 to 12 GPH, with the same cabin and two doors that the Sierra has. But the big plus that the Commander has going for it is the STCd Garrett turbonormalizer available from RCM Normalizing in Big Piney, Wyoming. This clean installation results in cruise speeds of 150 to 164 knots, depending on altitude, and an outstanding climb rate.

The turbo-installed for about $17,000-doesnt change the 2000-hour TBO of the IO-360. The performance is similar to the normally aspirated 114B Commander, for much less money. (Total cost would be about $65,000 to $75,000.)

I realize that the article mainly addresses non-turbocharged airplanes for easy transitions. And thats exactly how we moved up, buying a stock 112 and getting familiar with a complex airplane before adding the turbonormalizer. But the availability of the turbo was the big factor in making the decision to go with the Commander. A three-blade Hartzell prop is also STCd for the 112. We had been flying the turbo about 12 months and added the three-blade recently. We are very pleased with both.

In the looks department, put the 112 next to a Sierra on the ramp and see how many choose the Sierra. Thats where the word pathetic might pop up. We think the 112 Commander, with the normalizer option, is the best of all worlds as a retrac step-up and it deserves a close look.

-Jay Daly
Chandler, Arizona
Contact RCM Normalizing, Inc. at 100 Big Piney Airport Road, Big Piney, Wyoming 83113-0000, 307-276-3386.

Lap Those Valves
I read with interest your recent article about Good Jugs, Bad Jugs in the July issue of Aviation Consumer. Its very discouraging to read that brand-new cylinders are sold and not up to proper specification.

Most of my experience is with fairly high-tech motorcycle engines, high specific output engines producing a lot of horsepower for their size, such as my Yamaha 1000cc, (60 cubic inches) has produced over 160 BHP on a dyno.

Shortly after it was broken in at about 1000 miles or so, I did a cylinder leakdown test and to my dismay, I found 15 to 20 percent leakage past the valves. When I complained to the factory, I learned that they cut the valve seats at different angles and expect that at about 10,000 miles, they have beaten themselves into a good seal.

I removed the cylinder head and lapped the valves-all 20 of them. Considering the high cost, low volume and low technology of aircraft engines, theres no excuse for the manufacturers not to get it right.

-Neil Dale
Tucson, Arizona

Tiara Defended
I usually just grimace about once a year when you refer to the ill-fated Tiara engine. The Tiara 285 HP engine was fitted to a four seat retractable made by Robin Aircraft in France for instrument training. Some were sold in the European GA market.

I operated one until recently. When Continental stopped supporting the engine, the aircraft was re-engined with the 250 HP Lycoming 0-540, which had always been an option for the airframe. These aircraft are still flying.

Rolls Royce built the Tiara engine under license and the French Air Force Tiara spares holding was purchased and brought to the United Kingdom. Tiara engines can still be rebuilt here by an ex Rolls Royce engineer who worked on the original program. One or two components have supply problems but in general, its no harder to get fixed than my current IO-520.

The Tiara aircraft is similar in looks to a TB20 but is faster and with a 100-gallon fuel capacity, range is phenomenal. It will carry four adults and full fuel. The engine was fitted with a Hoffman three-blade fiberglass-sheathed wood prop. Turning at half speed, it is very quiet indeed.

I think the Tiara had the potential to be an excellent engine. The problems were not with the concept but the ancillary systems. I think these would have been solved in time.

The main issues were to keep the fuel system set up exactly right and starting the engine when hot. Hot starts in a big engine are always problematical but the Tiara was more exciting than average. It had electrically heated fuel injection through an extra nozzle for starting, plus a two-speed fuel pump. Too little fuel and you had no chance of a start and too much and you had a fire. (Twice for me.)

The best double whammy was for the engine to quit on the roll out after landing, because the injection was not set up quite right. A hot start in these circumstances was impossible, thus a blocked runway, irate ATC and an embarrassed pilot. Perhaps a dozen of these aircraft are still flying in Europe and one that I know of in Canada.

-Jim Thorpe
Herfordshire, England

Oregon Aero

After searching through numerous back issues of AC I decided to purchase a Pilot DNC XL headset. I instruct between 100 and 200 hours a year and wanted the additional ANR hearing protection.

I purchased the headset from Oregon Aero at the EAA AirVenture. Oregon Aero was selling the headset at the same priceeveryone else was except they added their deeper ear seals, mike muff and headband.

After a short period of use I became dissatisfied with the headset because of poor fit. I called Pilot and they indicated they were aware of the problem and were working on a fix . They promised to send me one. I have not received it yet. After another couple of months I called Oregon Aero and explained the problem I was having with the headset.

I told them I wanted to return the headset for a credit. They were helpful and requested a letter indicating why I was unhappy with the headset and a copy of my charge slip, both were provided. Oregon Aero is a class company. They didnt hesitate to satisfy this customer.

Hats off to Oregon Aero.

-Reuven Silberman
via e-mail