Sukhoi Civil Aircraft hopes to make the first engine runs on its PowerJet SaM146-equipped Superjet 100 this week as it awaits authorization to begin flight tests that it now says could take place in about a month’s time. A second aircraft, now undergoing completion, could fly before June, according to Sukhoi.

Initial engine runs on the first aircraft will be followed by taxi and shimmy tests. Approval to fly hinges on the outcome of almost 50 hours of trials at Zhukovsky, Russia, running since early December with an Ilyushin Il-76LL testbed.

Engineers must analyze the results of the initial 42 hours of engine running achieved during 22 flight tests before the Central Institute of Aviation Motors in Russia clears Sukhoi to fly the new regional jet, which remains scheduled for certification and delivery to Aeroflot by year’s end. PowerJet claims the flights and attendant ground tests have been successful, achieving “all expected performance objectives.”

Tests included flight-envelope exploration, validation of performance, operability, restart logic and relight, demonstrated acceleration and deceleration, and “flame-out” margins. Other topics were in-flight validation of full-authority digital engine control software and fan-blade flutter margin, and verification of general behavior, including stress and vibration levels. Engine flight trials are scheduled to resume in about three months’ time.

Engine running on the Superjet is scheduled to begin this week using two compliance engines delivered earlier this year to Sukhoi at Komsomolsk-on-Amur in far eastern Russia. PowerJet is building eight development engines and 10 “compliant” units, including the two now fitted to the aircraft. It has demonstrated a thrust of 18,500 pounds during more than 800 hours of testing.

Preparations for the Superjet’s first flight continue with in-house systems running, and frequency and ground tests. Sukhoi also has been working on second and third aircraft. For example, the wings and control surfaces have been attached on the second machine. The fuselage of the third aircraft has been assembled.

Current plans cover assembly of six aircraft, including individual static- and
fatigue-test examples. The Russian manufacturer is upgrading its production facilities in preparation for building up to 70 aircraft a year.

Engine partner Snecma, a member of the Safran Group and part of the PowerJet joint venture with Russia’s NPO Saturn, has corrected erroneous reports (published in good faith in AIN) that 1,500 hours of testing was required before the Superjet could fly, and that the Il-76LL had been operating from the southern French test facility at Istres. In fact, only 150 hours are required for engine certification, while the aircraft will not go to Istres until it begins a further batch of tests.