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Aviation History
1998
1998 - 1456.PDF
ENGINES The STC, developed by Tulsa, Oklahoma- based Intercontinental Jet, received US Federal Aviation Administration certification in April. Kenny Morgan, Intercontinental Jet's man ager of customer service, reports that under the STC the two Mu-2 models, powered by TPF.331 -5-252Ms, will be re-engined with the -10T-511M. The modification facility is also pursuing another STC to cover the Mu-2J,K,L and M models. Certification is expected by the fourth quarter of this year. "This STC will use the AlliedSignal TPE331-10AV as an upgrade from the TPE331-6-251 and -252M engines,'" Morgan says. With approval of the second STC, AlliedSignal estimates, as many as 260 Mu-2s will be candidate aircraft for the upgrade. As Morgan explains, the two separate STCs address differences in propeller speeds between the two engines. The -10T-511M model pro vides a propeller speed of 1.591RPM at 100% engine RPM. The -10AV delivers a propeller speed of 2,000RPM. Few airframe modifications are needed under the STC. What is required is a new exhaust pipe installation and some rewiring to accommodate the EGT indicator. Also required are airframe bleed air modifications in the engine compartment. Intercontinental Jet, says Morgan, expects to complete its first Mu-2N conversion by mid- June. "We expect that performance will be equal to or better than that of the Mu-2 Marquise," he says." I lie I A As certification pilot reported that on our first P-model conversion, the rate of climb at 5,000ft [1,500m] was 3,700ft/min [19m/s] at a best climb speed of 140kt [260km/h]. The pilot also reported that the air craft equalled or exceeded the cruise speeds, as published in the pilot operating manual, for the Mu-2 P model." For operators who elect to upgrade to the TPE3 31-10T-511M under the continued time option, the total cost of the programme - including removal and re-installation - is S273,000 for both engines. The overhaul and convert option is priced at $403,000. The same prices, Morgan expects, should apply to the -10AVengine upgrade. One of the first STCs developed for a GAair- craft under the TPE331-10 conversion pro gramme was for the Cessna Conquest II. That STC, developed by West Star Aviation of (irand Junction, Colorado, was issued by the FAAin February 1992. Russ Williams, the com pany's vice-president of business development, notes that, of the 362 Conquest lis produced between 1978 and the end of production in 1986, about 3 30 are still in service. Popular as an executive transport and an owner-flown air craft, the Conquest II was certified for single pilot operation, and carries up to 10 passengers. "We have converted 155, or 47%, of the exist ing fleet, from the origina 11 PF.331-8 powerplant to die -10X series," Williams says. "VVe are cont inuing to average about two aircraft a month." r.! • i i ',? i A r West Star Aviation This -10 powered Conquest II was painted in tiger nun kings for a round-the-world rally in 1994 He stresses that the project is a joint effort between West Star and AlliedSignal. "We are ;i major service centre for the TPF331. Because of this, we felt that the modification would be far more marketable by working with the factory on the upgrade programme. In fact, we are the only factory-authorised facility to perform this upgrade on the Conquest II." As Williams explains, costs vary in accor dance with the work. For instance, Conquest II operators which simply want to overhaul (and not upgrade) their TPE33 l-8s can expect to spend about $290,000 for both engines. Those which choose the continued time upgrade to the -ION model will spend slightly more - $302,000 for both engines. The most expensive option, which involves the full overhaul and conversion, costs S454,000. TIME CONVERSION PRICE BENEFIT Xol surprisingly, the majority of West Star's customers selecting the upgrade - 115 of the 155 - have picked continued time conversion. Only 40 have chosen to overhaul and convert. As Williams explains, along with the price advantage, the operator has the benefit of the 5,000h TBO on the upgraded engine. "If an owner decides to do the upgrade at 2,000h, for instance, he can go all the way to 5,()00h before looking at a major overhaul," he says. "When we consider that the average Conquest II is used about 300 flight hours a year, you can see the long term savings." But the significant savings are realised during major maintenance events, as Williams points out. "On the -8 engine, the hot section overhaul was running about $85,000-90,000 per pair of engines. It's now about $60,000 per pair for the -1 ON, but we have seen costs as low as $39,000 for the pair," he savs. "A complete overhaul of the -8 is about S290.000 for the pair, but $260,000 for the - ION. In fact, reserves for hot section and overhaul have been reduced from SI25 per flight hour to $65-70 per flight hour for both engines." Williams reports that, to date, about 90% of West Star's customers reaching overhaul inter vals on Conquest lis equipped with the original TPE331-8s have elected to upgrade. He adds: "One other important reason for this is that it will enhance the resale value of the aircraft, often by as much as $250,000-S300,000. As an example, the price of a Conquest II with -8 engines is running between S900,000 and $1.5 million on the resale market. But we are seeing that the -1 ON upgrade is increasing those values to between S1.2 million and $1.8 million." I le stresses that the STC for the Conquest II engine upgrade requires no airframe or nacelle mollifications. "Even the instruments relating to the engines are the same. About all we have to do is install new engine mounts and hoses." Owners of Beech King Air BlOOs were first offered the upgrade option in 1995, when the FAA certified an STC developed by the Springfield, Illinois, facility of Garrett Aviation Services (GAS). The STC called for the con version of the TPE331-6-252B engine to the -10AV-511B model. According to Doug Clarke, GAS Springfield's customer support administrator, the programme has accounted for six aircraft since the first upgrade was com pleted in mid-1996. Between the mid-1970s and early 1980s, 137 King Air BlOOs were built. Of those, Clarke says, about 75 of the single-pilot certified, 8/10- passenger aircraft are considered candidates for the conversion, worldwide. "Akey advantage of the upgrade programme is that it offers a viable maintenance option for those who wish to retain the aircraft," he says. The STC for the King Air B100 retrofit includes modifications to some of the compo nents and the airframe. One of the most significant involves a new propeller from Hartzell. In addition, the engine exhaust pipes 38 FLIGHT INTERNATIONAL June 3 - 9 1998
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