Su-25 tender

Krassimir Grozev and Alexander Mladenov detail Bulgaria’s tender for overhauling its Su-25s

Alexander Mladenov

A TENDER for overhaul, service life extension and some minor upgrades of the entire Bulgarski Voenno Vzdushni Sili (Bulgarian Air Force fleet) of ten Su-25K and four Su-25UBK attack aircraft was released by the Bulgarian Ministry of Defence on August 21. The work will be carried out under a framework agreement, where the Ministry of Defence can place orders each year for upgrade of a number of aircraft according to the available budget.

Overhauled airframes have a service life of at least 800 flight hours, while the aircraft’s R-95Sh turbojet engines will be re-delivered following the overhaul with 500 hours of remaining service life. The aircraft’s total service life must be extended to 40 years rendering the aircraft good for use until 2028.

The forecasted value of the work covering 14 aircraft is BGN 41 million, which is only sufficient for less than half of the fleet. However, the tender contains an option that can be exercised following a Bulgarian Government decision to increase the budget up to BGN 82.51 million.

The original service life of Bulgaria’s Su-25 fleet expired ten years ago; aircraft have been kept flying at a low operational tempo thanks to a series of life extensions, independently undertaken by the Bulgarski Voenno Vzdushni Sili engineering service at virtually no cost.

Currently the Bulgarski Voenno Vzdushni Sili has a handful of Su-25s with extended service lives, which are kept in operational condition.

The service life extension announced on August 21 will be undertaken together with a general overhaul, with a requirement that all work is authorised by the aircraft’s design authority, Russian company United Aircraft Corporation (UAC).

According to the publically-released tender information, the singleseat Su-25Ks remaining in service racked-up between 741 and 1,053 flight hours, while the two-seat Su- 25UBKs logged between 1,244 and 1,570 flight hours.

According to the Ministry of Defence’s market research, only two companies have the required technical capability to undertake the overhaul, service life extension and minor upgrades in accordance with the Bulgarian requirements; both have received a request for proposal. The first is UAC’s 121 ARZ, an aviation MRO company at Kubinka in Russia, and the second is the 558 ARZ company from Belorussia.

Tender requirements also contain a draft schedule of the work, which calls for two Su-25UBKs and two Su-25Ks to be cycled through overhaul, life extension and upgrade in 2019, at a forecasted price of BGN 20.83 million. These will be followed by two more aircraft in 2020 priced at BGN 22.83 million, four Su-25Ks in 2021 (BGN 24.87 million), and the last two Su-25Ks in 2022 (BGN 13.98 million).

The technical specification calls for adding provisions for new self-protection equipment, a new weapon control system compatible with the R-73 air-to-air missile, new radios and navigation aids.

It remains unclear if funding will be available to cover the entire 14-aircraft fleet, given the pressing need for investment in maintenance of other aircraft types in the Bulgarski Voenno Vzdushni Sili’s otherwise crippled fleet, and little prospect for a sizeable near-term increase of Bulgaria’s defence budget.

Currently, both the 558 ARZ and UAC offer a Su-25 general overhaul for about BGN 8.4 million. Consequently, it is realistic to predict that up to ten aircraft, including all four Su-25UBKs, will undergo the programme of works, but only if a contract is signed, and the maximum forecast budget is provided by the Bulgarian Ministry of Defence. A so-called minimum contract would involve between just four to six aircraft.

In August 2017, Bulgarian defence minister Krasimir Karakachanov called for the Air Force’s current fleet of Russian-made fighters and strike aircraft to receive urgent funding to maintain their airworthiness. According to Karakachanov, by investing in refurbishment, the Su-25 fleet can be made good for service until about 2030. In addition, Bulgaria’s 15-aircraft MiG-29 fleet is also set to remain in service for the long-term, thanks to a framework agreement signed with RAC MiG in March 2018 covering spare part supply and maintenance services until 2022 at a cost of BGN 81.2 million.

Bulgarski Voenno Vzdushni Sili Su-25K 253 with its drag chutes extended after landing at Bezmer Air Base, home of the 22 Shturmova Aviacionna Basa (22.ShtAB or 22 Wing). Alexander Mladenov