In the end of 2016 Ukraine’s State Aviation Administration issued the first ever airworthiness directive regarding Antonov An-148/158 regional jets. The manufacturer’s press office told the Russian Aviation Insider that Directive DLP-0888-16 dated November 9, 2016 implies An-148/158’s fuselage structure to be modified to provide better ‘testability’ of the aircraft. The document was issued after parts of the fuselage skin and outer rings of the 23rd former (in the vicinity of stringer #28) on An-148-100 and An-158 aircraft were discovered to suffer excessive loads. The directive says the entire aircraft fleet of this type shall be modified.
The official document signed by Head of the State Aviation Administration Alexander Bilchuk goes that the directive was elaborated as a follow-up of the aircraft loading analysis based on data from BUR-92A flight recorder, actual stress assessments at various structural parts, as well as fatigue life performance simulation for critical fuselage parts and overall endurance test results.
In order to carry out the instruction of the Ukrainian authority the aircraft’s fuselage in the area of former #23 will need to get modified and undergo non-destructive tests.
The modification procedure will involve all operational An-148/158 airplanes regardless of permanent location. Currently, that makes 40 aircraft including five An-148s and six An158s produced by Antonov and 29 An-148s assembled by Voronezh-based VASO facility in Russia.
Antonov’s press office underlines that any directive by the aviation authority is mandatory. In its reply to the question on who would pay for the modification works the Ukrainian company said the works are performed within service contracts with aircraft operators.
Apparently, the required modifications can be provided by An-148/158-certified maintenance and repair organizations, such as Antonov and VASO. However, the works will not necessarily require participation of Antonov’s engineers.
Service Bulletin #148-53-159 defines deadlines for the modification but does not require withdrawal of the entire fleet from service. Particularly, An-148s and An-158s are to be modified before 3,000 and 2,800 flights in service, correspondingly. The airframes which have already exceeded the numbers will be modified during the next maintenance check. The procedure takes no longer than two working shifts.
Russia which operates the majority of An-148’s took the news in stride. United Aircraft Corporation (UAC, VASO parent company) told the Russian Aviation Insider that VASO will take Antonov’s recommendations into account in the best interest of An-148/158’s operators.
All VASO-produced An-148s are currently operating in Russia with major part of them being used by government facilities like Ministry of Defense, Ministry of Emergency Situations and the government’s special air wing. Seven aircraft are in active commercial operation including five An-148-100Es in Angara’s fleet and two An-148-100V in the disposal of Saratov Airlines.
Both carriers have reported the Russian Aviation Insider that the aircraft are in full service, the modifications will be performed in accordance with the service bulletin.
Remarkably, the airworthiness directive was issued right at the time when Saratov Airlines was accepting delivery of its first An-148-100V. It was supposedly one of the reasons why the airline was not able to promptly introduce the aircraft into operation. The aircraft with RA-61703 tail number performed its first commercial flight under the flag of the Saratov-based carrier one and a half months later, on December 26, 2016.
Apart from Russia, two An-148s are operated by North Korean Air Koryo. Six stretched An-158s are owned by Cubana de Aviacion.
By Artyom Korenyako
Russian Aviation Insider
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