Russian aircraft manufacturer Sukhoi has started flight-testing the long-range version of its Superjet 100. But if the SSJ program is to become a success, the technical flaws that affect the baseline version must be conquered.

The first prototype of the SSJ 100LR made its maiden flight Feb. 12. The variant has a range of 4,578 km (2,845 mi.) compared to 3,048 km for the basic type. The long-range version can carry more fuel and is powered by NPO Saturn-Snecma SaM146-1S18 engines that provide 5% more thrust than the standard SaM146s.

According to United Aircraft Corp., Sukhoi Civil Aircraft Corp.'s parent company, the SSJ 100LR trials will take 3-4 months. Certification of this version is slated for 2014. Gazpromavia is signed on to be the first operator. The carrier, a subsidiary of Russia's energy giant Gazprom, placed an order for 10 SSJ 100LRs in 2011.

Sukhoi officials meanwhile say measures are underway to improve the appalling reliability record of the Superjets already in service. Because of a range of technical issues, four of Aeroflot's 10 SSJs were temporarily grounded. They were cleared to resume regular flight operations earlier this month. The pressure on Superjet's civil arm is mounting now that the first export deliveries to Indonesia-based Sky Aviation and Mexico-based Interjet are imminent. Laos-based Lao Central received its first aircraft Feb. 15.

Aeroflot stated in an internal presentation in January that its SSJ 100s were involved in 24 technical mishaps in 2012. The aircraft was therefore responsible for 40% of the total technical incidents for Aeroflot's fleet of 125 aircraft during this period. Most common were problems with the SSJ 100's air conditioning system. Other issues that cropped up frequently affected the aircraft's flight controls, landing gear, fire protection system and engines. Aeroflot's SSJ 100s have logged a total of 17,313 flight hours or 9,186 flights as of January.

But Andrey Nedosekin, Sukhoi Civil Aircraft's senior vice president for post sales support, says the major problems have been identified and repairs are already underway. A service bulletin addressing the erroneous engagement of the air leakage detection unit—a part of the overall air conditioning system—has been issued and implemented for all aircraft at the production site. Sukhoi announced that all necessary changes will be implemented across the operating fleet by summer.

Another service bulletin addressed a slat extension fault after a new design was validated during additional bench tests. According to Nedosekin, the corresponding design improvements were implemented on the four grounded Aeroflot SSJ 100s. A schedule to correct the balance of the affected aircraft is being worked out with all carriers, according to Sukhoi. The manufacturer will be compensating the airlines for financial losses incurred during the grounding.

The landing gear defects were detected on only two aircraft in January and, according to Nedosekin, were not system-related. A mechanical defect prevented the landing gear from retracting, but the issue has been addressed by working with the unit's manufacturer—Messier-Bugatti-Dowty.

This year, Sukhoi plans to replace seven of Aeroflot's SSJ 100s with new so-called full-version aircraft. The first, slated to arrive in March, features individual air vents for passengers, more lavatories, a new weather radar with windshear detection mode and an improved flight-management system. Aeroflot asked for these requirements after it inked the initial contract for 30 SSJ 100s in 2005. To avoid delivery delays, the carrier agreed to take the first 10 aircraft in a more basic configuration provided they would be replaced later. The other three aircraft will be replaced at some point even further in the future. Nedosekin says the returned SSJ 100s will be offered to other customers.

Another Russian airline, Yakutia, began SSJ 100 operations at the end of January. Yakutia's two SSJ 100s are configured in a 93-seat twin-class cabin layout (eight seats in business class, 85 in economy). The East Siberia-based carrier faces harsh winters, so the performance of its SSJ 100s is likely to differ from that of Aeroflot's, which operate in the milder central regions of Russia. In December 2012 the Commonwealth of Independent States' (CIS) Interstate Aviation Committee issued a supplemental type certificate verifying SSJ 100 operations in northern latitudes at temperatures up to 78F and down to -54C.

The launch customer for the SSJ 100, Yerevan, Armenia-based Armavia, is unlikely to resume operations of its only aircraft of the type. It was delivered to the Armenian flag carrier in April 2011. In summer 2012, Sukhoi refused to return the aircraft from a maintenance check, stating that the carrier was severely in arrears. The matter is still in dispute.

Nevertheless more foreign airlines are to start SSJ 100 operations this year. Sky Aviation ordered 12 aircraft while Lao Central signed for three aircraft with an option for six more. Type certification for the aircraft was issued in Indonesia in November 2012, followed by Laos in December.

Sky Aviation went ahead with its purchase despite the May 9, 2012, crash of an SSJ 100 prototype during a demonstration flight near Jakarta. In December 2012, the Indonesian aviation authority cited human factors and the absence of detailed terrain charts onboard as the primary causes of the crash.

Two green SSJ 100s intended for Mexican carrier Interjet are being completed in Venice by the Russian-Italian joint venture SuperJet International, the entity responsible for sales in Western markets.

Sukhoi plans to increase the annual rate of SSJ 100 deliveries to 30 aircraft in 2013 and to 60 in 2014. In 2012 the company rolled out 12 airframes and delivered seven. The official backlog stands at 179 aircraft. Plans are to certify the Sukhoi Business Jet version by the end of 2014.