Checks on the flight controls of Sukhoi Su-29 and Su-31 aerobatic aircraft are being urged after the fatal crash of an Su-29 near New Orleans on 21 March was blamed on an incorrectly assembled elevator-control system. The US National Transportation Safety Board (NTSB) has called on the US Federal Aviation Administration to issue a directive requiring control-system checks.
The NTSB believes that the bolt attaching a control rod to the elevator-control bellcrank fell out after the cotter pin securing a nut came loose. An inspection of three partially assembled Su-29s at Pompano Air Center (PAC), Pompano Beach, Florida, revealed control-system cotter pins which were not flared, or only partially flared, and which could fall out in flight.
Two-seat Su-29s and single-seat Su-31s are manufactured and test-flown by Sukhoi. The wing, tail and gear are then removed for shipment to PAC, which re-assembles the aircraft for delivery worldwide. A total of 40 Su-29s and 12 Su-31s have been delivered to customers.
In April, PAC instructed owners to inspect the flight controls. It says that the inspections have revealed no assembly defects. According to the NTSB, PAC does not inspect the work performed by Sukhoi and the FAA does not require evidence of an inspection before certificating the aircraft.
Source: Flight International
