STC'd Conversion Installs 1,000 SHP Garrett TPE-331 Engines, Upgraded Avionics

By ANN Correspondent Juan Jimenez

How do you take one of the most successful business aircraft in the history of aviation and make it better? You take the bull by the horns and do it yourself.

That's what the Kilo Alpha 290 conversion does for the Raytheon/Beechcraft King Air C90 and E90 series twin turboprop aircraft. Two well-established leaders in the specialty aircraft industry back the conversion. Murray Aviation is an operator of a fleet of turbo-props and a designer/builder of airframe cargo doors. National Flight Services is the largest independent overhauler facility of TPE 331 engines with over 3,000 completed to date.

Mark Murray, co-owner of Murray Aviation, originally conceived the conversion. Murray had a King Air A90 with PT6 engines, and an MU-2 with TPE-331 engines. He considered the King Air to be underpowered, the complete opposite of the MU-2, regarded by many as the aviation equivalent of a thoroughbred race car. He decided to combine the best of the two - a big wing on one, a big motor on the other - and came up with the concept of upgrading the engines on the King Air to improve its performance.

Garrett has invested significant time and effort into improving their TPE-331 engine, which at one point was known in the industry as the "Garrett Grenade." The engine selected for the upgrade is the TPE-331-10AV-511KA, a 1,000 shp engine, de-rated to 715 shp for the Kilo Alpha installation. Unlike the engine it is replacing, the Garrett engine has double the TBO, a whopping 7,000 hrs.

The results in terms of performance are impressive. Initial flight tests demonstrated 600 ft takeoff rolls. Setting power at 2,000 rpm at FL240 resulted in an impressive 285 kt cruise. Climb performance is equally impressive. Between FL130 and FL190 the aircraft can climb at a 2,000 fpm at 165-180 kts IAS. At 100% rpm Murray's A90 was getting a 1,300 nm zero-wind range. Pull back to economy cruise and that number increases to 1,500 nm. An upgraded E90 results in 1,700 and 2,000 nm, respectively.

According to company documents, an analysis of operating costs between a stock C90 and a Kilo Alpha 290 converted aircraft shows that direct operating costs are dramatically improved as well. Assuming a mission profile of 15 trips of 600 nm, 30 of 1400 nm and 25 of 1800 nm a year, engine reserve costs are reduced from $120 to $52 and change. The biggest reason for this is the near doubling of the TBO and engine midlife inspection cycles. Annual direct operating cost savings is calculated at just over $73,000. The numbers and charts the company is presenting to back up these numbers are available on its website, listed below.

The conversion also includes the installation of a new five-bladed McCauley noise reduction propeller using shorter blades than the factory installed props. This has the effect of reducing noise by reducing the tip speed of the prop blades to below supersonic speeds.

A new exhaust stack is also installed which redirects boundary layer airflow and mixes it with the exhaust to virtually eliminating the sooting King Air's are so well known to suffer from.

National Flight Services in Lakeland, Florida, has been selected as the national installation service for the Kilo Alpha conversion. National Flight has accumulated experience through the overhaul of over 3,000 Garrett TPE-331 engines, the largest number of any authorized overhauler. In addition to the engine conversion and avionics upgrade, National Flight Services can also install Raisbeck upgrades such as their Aft Body Strakes.

Currently, the conversions are being completed in approximately 10 weeks. Kilo Alpha and National Flight Services are working to reduce the time to a total of 6 weeks.

FMI: www.kiloalpha.com