What happened
On February 27, 2011, a McKinnon G-21G, registration N221AG, was preparing for a flight from Al Ain International Airport to Riyadh, Saudi Arabia. The crew had initially planned to perform a local circuit to familiarize themselves with the aircraft after a period of inactivity. After receiving taxi instructions and clearance for takeoff from Runway 19, the aircraft began its takeoff roll normally.
However, shortly after liftoff and during the initial climb phase, the aircraft veered to the left. The aircraft impacted the ground at Taxiway F, between Taxiway Kilo and Lima, with a nose-down and left-roll attitude. The aircraft traveled approximately 32 meters from the point of impact before coming to a complete stop. A post-impact fire broke out, consuming much of the aircraft's structure. There were 4 fatalities among the four people on board.
The investigation
Investigators from the GCAA AAIS, in coordination with the NTSB, conducted a detailed examination of the wreckage and the engines. The investigation focused on the mechanical state of the two TPE331 series turboprop engines. Laboratory examinations of Engine No. 1 revealed significant damage, including heavy rubs on the compressor impeller shroud and bent blades on the second-stage compressor impeller. Engine No. 2 also showed evidence of internal rubbing on the compressor housing and impeller.
Analysis of the engine components, specifically the bending of the blades in the direction of rotation, suggested that both engines were still rotating at the time of impact. While most flight instrument indicators were rendered unreadable due to heavy soot, a witness mark on the Engine No. 1 torque indicator was found near the 25 psi marker. The investigation also reviewed aircraft maintenance records, which showed recent modifications including the installation of a Garmin G600 flight display, but found no significant deficiencies in the aircraft's documentation.