Paul Duffy/PERM
The last seven years have been difficult for the Russian aviation industry. Long accustomed to producing to Soviet state orders, the industry's finance and income also came from the same source. Now in crisis, most state-owned companies in the industry are waiting for state rescue.
If the airframe designers and manufacturers have had a tough time since the end of the Soviet Union, the engine industry is in even worse condition. Most Soviet-era engines date from the 1960s and have seen little modernisation. Only one new, non-derivative, turbofan engine was approved for construction in the 1980s, for mainly commercial use - the 35,000lb thrust (157kN) Soloviev D-90A, later renamed the PS-90A (to commemorate Pavel Soloviev).
Development of the new engine began in 1983 and the first examples entered bench testing in 1985. Flight testing started in 1987, on an Ilyushin Il-76LL (LL for Flight Laboratory), with one of the aircraft's four D-30KP engines replaced by a PS-90A. In 1988, its first application, the new Ilyushin Il-96-300, made its first flight, followed a few months later by the Tupolev Tu-204 in January 1989.
But by then the Soviet Union had begun to run out of money, and the budgets to develop, flight test and certificate new aircraft and engines started to be curtailed. Target operational introduction for the new aircraft slipped from 1992 to July 1993 for the Il-96-300, and to January 1996 for the Tu-204. Developing financial problems of Russia and the CIS meant that airlines had little money to buy new aircraft. While the designers had expected the PS-90A to enter service in reasonable numbers, only a trickle resulted, which greatly impeded the engine's development.
"If the Soviet Union had lasted three more years," says Alexander Simonov, deputy general director of Aviadvigatel (formerly the Soloviev design bureau), "we could have resolved most of the engine's teething troubles. Normally, the first year's service highlights any problems, but with only two aircraft in airline service in the first year, not enough engines were operational to build up our base of experience".
The PS-90A was designed to provide 35,000lb take-off thrust, with international standards of fuel consumption and maintenance reliability, for a new generation of Soviet aircraft. Its core was intended to be the basis for a range of engines from 18,000lb to 44,000lb thrust. The PS-90A was selected over the Kuznetsov/Samara NK-93, a 40,000lb thrust engine, because its fuel consumption was better and maintenance costs lower. Soloviev and Kuznetsov were long term rivals, and thePS-90A's selection was well received in Perm, where Aviadvigatel is based. The bureau's premises adjoin a major engine production factory today called Permski Motornaya Zavod (PMZ), or Perm Motors. Production of the new engine was assigned to PMZ.
The first PS-90s were built by the design bureau, which completed 23 engines that were used in the test and early development stages. The first production PS-90A also joined the test programme, and only then were engines fitted to the Il-96 and the Tu-204. When the PS-90A entered service on the Il-96-300, it was soon apparent that, as with any other new engine, some modifications and redesign were needed.
Under the old Soviet certification system, designers were required to prove that the engine could operate satisfactorily for 1,000h. The lead engine had then to be fully stripped for a detailed examination and any modifications incorporated before certification. Thereafter, lead engines would be removed and examined at specified periods and the results of these tests would lead to life extensions as appropriate.
The Western system tends to start with target service lives and tackle problems by airworthiness directives as they arise. The Soviet system was more cautious, and as more commercial attitudes began to be felt in Russian industry, it left the industry at a disadvantage.
By the time the PS-90A-powered Il-96-300s entered service with Aeroflot-Russian International Airlines in 1992, the carrier had begun to operate Airbus A3l0s powered by the General Electric CF6, one of the most reliable Western engines. It was soon apparent that the untried PS-90A did not compare favourably.
By now, Russia was undergoing the change brought on by the collapse of the Soviet Union, and money was becoming tight. Like most other major industries, Aviadvigatel and PMZ were (then) fully state owned and, with 45,000 workers between them, relied almost entirely on state orders and funds. The management costed the work needed to sort out the engine's difficulties, and presented a programme for the work to the Government. After some months, $140 million was approved by the state to be paid over the three years, beginning in 1995.
REDESIGN WORK
The state-approved programme involved considerable work, and, with Pavel Soloviev now retired (he was to die in 1997), the new general designer Alexander Inozemtsev and his team began the redesign work. It included:
improving the combustor, which increased the engine's service life and improved the operating environment of the first turbine stage; eliminating the centre bearing from the turbine shaft, the simplified design removing several faults; introducing a new final compressor stage with a higher cyclic durability; installing improved igniter plugs and bearings, using higher quality materials; improving the second compressor stage; and installing discs and blades capable of withstanding higher stress loads.Money promised by the government was, at best, coming in much smaller amounts than expected. Although the company will not comment, other Russian sources indicate that probably no more than 20% of the $140 million was paid. This left a considerable amount to be found elsewhere.
Aviadvigatel's general director, Yuri Reshetnikov, and his team went looking for new customers. It found the Russian oil and gas giant Gazprom, which needed turbines to pump fuel along its pipelines and it developed the GTU-12P and GTU-16P gas turbines from the PS-90A. That gave PMZ a production line with a willing customer and began to bring cash back into the factory.
The company also looked for foreign partners: in 1991, United Technologies, the parent company of Pratt & Whitney, began to look hard at the then Soviet Union. Its president, George Davies, took a long-term view and decided that the market in the region, while not an easy one to enter, would be worthwhile in the long term. A P&W team, led by Jack Carney, looked at all the major engine facilities in the former Soviet Union and decided Perm was the only one in which they were interested. The plan was to jointly develop the PS-90P, an uprated and improved version offering 40,000lb take-off thrust. But a change of management at Aviadvigatel and Perm Motors brought that proposal to an end and led to a shift to a partnership with General Electric.
Then a powerful Russian conglomerate, Interros, took a major shareholding in Aviadvigatel and PMZ, and Reshetnikov resumed his position. "Now," says Reshetnikov, "we have begun to work with Pratt & Whitney again. Our co-operation is expanding. Rather than go ahead with the PS-90P, we have agreed to develop the PS-90A2, a less deeply modified version which should bring improvements to our basic engine."
Although there are only 12 PS-90A-powered aircraft in operation (there are six more development aircraft powered by the engine, plus eight Tu-204s that require post-certification modifications), operational reliability has grown dramatically; from 2,010h maximum time on wing in early 1997, to 6,000h in November 1998.
The improvements in the engine's reliability has been noted in the MAK (Interstate Aviation Committee) Aviaregister, where the engine's certification has been amended to allow on-condition maintenance - the first such approval for any Soviet/CIS engine.
Another five engines are nearing 6,000h on wing, while the high-time engines, after one overhaul, are reaching 9,000h. "We are conscious that some Western engines have reached 30,000h on the wing, but these are a bit exceptional," says Simonov. "A reasonable average time is probably around 7,500h. We are getting close to this with our lead engines, and we'll continue our work to improve reliability. Our engines have no total life limits; once a major overhaul has been completed, they can return to service until the next overhaul is needed."
Soviet tradition was to allocate engine overhauls to a particular factory. This has not been done with the PS-90A, although Bykovo Aviation Services, formerly Plant N402, plans to set up to maintain the PS-90A. PMZ, meanwhile, has begun to do the work itself.
SUPPORT COMPANY
"We started to do it because of the problems our first PS-90A customers were having with the engines," says Vladimir Kobelev, director general of PMZ. "With Aeroflot and Ilyushin shouting at us, we developed a 'power-by-the-hour' arrangement which we also offered to our later customers. We set up a specialist engine support company, with about 100 engineers to support the engines at each of the airports served by them. I have to say that the early engines cost us quite heavily, but as they came in for overhaul at our new repair facility, they were modified to today's standards, and the modified ones, plus recent production engines, are proving to be profitable."
Finances remain tight. "The factories producing the aircraft which use the PS-90A," says Reshetnikov, "have great difficulty in paying us for them. So last year we took two Tu-204s from Aviastar in part settlement of their debt, and PMZ has set up a subsidiary to lease them out; one has gone to Perm Airlines, our local carrier, and the other to KMV in Mineralnie Voda.
"This arrangement is difficult for us - we needed the money to work out other problems and to pay our staff." Asked whether the leasing operation will be expanded, he says: "Currently, it is not profitable. But we will continue to examine the question. In the short term, it is unlikely.
"Today, we are continuing our work to improve the engine [the PS-90], and with Pratt & Whitney, we are developing the PS-90A2. We are thinking about expanding the range of power availability, but a primary concern would be to have an application for any higher or lower thrusts. The CIS aviation industry is in difficult financial shape. We will need to be sure that we have a market.
"Although the engine life is the same for the Il-96 and the Tu-204, the probable limit is in cycles - on take-off and climb, power is at its highest and engine loads and temperatures are also high. So the Il-96, with long flights taking from 9h to 14h, is achieving high hours. But the Tu-204, with flights of between 2h and 4h, is not yet achieving the high times we would like. We are working on this problem now. Most engine components, both hot and cold, should achieve up to 10,000 cycles, but some hot parts can be as low as 1,000 - by next year, we plan that this will rise to at least 5,000 cycles for every cold part, and 3,000 for the hot parts."
With Russian aircraft beginning to gain Western certification, it cannot be long before Russian aero-engines do the same. The PS-90 seems to be the logical frontrunner. "That would be a dream come true," says Simonov.
Source: Flight International
