Monday, September 1, 2008
Rotorcraft Report: Operators Address NOTAR Bulletin
Specialist Aviation Services recalled all 18 of its MD Helicopters MD-902s from police and emergency medical service lessees in early August while it investigated a control system failure.
On Aug. 8, an SAS Explorer on lease to Great North Air Ambulance of Durham, England, executed a run-on landing at its Denham Airfield base outside of London after the pilot experienced what the operator described as a dramatic reduction in yaw control.
Post-landing, SAS inspectors found a cable-and-rod assembly between the aircraft’s anti-torque pedals and the rotating cone on its no-tail-rotor (NOTAR) system was broken.
SAS notified MD, which issued Service Bulletin SB900-108 Aug. 12, covering MD900-series aircraft with serial numbers 900-00008 through 900-00128. It required, before further flight, a fluorescent magnetic particle inspection of the forward directional-control cable and modification to the rotating-cone control rod. SAS planned to have all its Explorers back in service by mid-August.
SAS Sales Director Nigel Lemon said the modification procedure called for in the service bulletin took maintenance personnel about 5.5 man-hours to complete. That did not include the time required to perform the fluorescent magnetic particle inspection.
Lemon told Rotor & Wing that he was very happy with MD Helicopters’ response to the problem, and reported that five of SAS’s Explorers had been inspected, modified and returned to service within a day of the service bulletin’s issuance.