History of the Flight
The flight departed Shoreham Airport at 1354 hrs on 2 December 2003, with the pilot in the left seat and a passenger in the right front seat. The purpose was to reposition the helicopter to Cheshire, with an intermediate stop near Hemel Hempstead. After an uneventful leg, the pilot landed at the site, keeping the rotors running for one minute while the passenger disembarked. Departing, the pilot received a VFR clearance from Luton Radar to route north-west not above 1,500 ft amsl. About one minute later, Luton Radar advised the pilot of an EasyJet aircraft crossing his nose. Approximately one minute after that, the pilot felt a severe vertical bump accompanied by a mechanical noise. He initially suspected a door had opened but confirmed it was closed. The helicopter developed significant vibration, so the pilot lowered the collective and entered autorotation. He broadcast a PAN call, reporting severe turbulence and a forced landing in a field. The pilot selected a field and performed a run-on landing. After a ground run of about eight metres, the helicopter pitched forward and rolled onto its right side. The pilot shut down the engine and fuel, then exited. Luton ATC was notified via mobile phone.
Damage to the Aircraft
Examination of the accident site showed the helicopter touched down with significant forward speed on soft, smooth ground. The skids penetrated the surface, causing drag that pitched the helicopter forward. The skids fractured at their forward attachments, and the nose contacted the earth. Main rotor blades struck the ground, and at least one blade passed through the tail-boom. Outboard sections of all blades separated, and the helicopter came to rest on its right side. The front right seat area sustained extensive damage; the pilot's occupied volume was uncompromised.
Pilot Experience
The pilot held a UK Private Pilot's Licence and an FAA Commercial Pilot's Licence with Instructor Rating. He had 4,900 hours total flying experience, with 1,100 hours on the accident type. In the preceding week, he had practised engine-off and run-on landings.
Meteorological and Surface Conditions
Weather was influenced by an unstable air mass with light easterly airflow. Visibility was good with cloud layers at 2,000 ft agl and above. Forecast wind at 2,000 ft amsl was easterly at 5–10 kt; surface wind at Luton Airport was 050° at 5 kt. The landing field had a young crop on reasonably level but sticky ground following recent rain.
Aircraft Description
The McDonnell Douglas Hughes 369E is a commercial version of a military light observation helicopter. G-LOGO, manufactured in 1991, had a five-bladed main rotor and mechanical flight controls without hydraulic assistance. It was equipped with two pilot seats and a range-extension fuel tank beneath two passenger seats in the rear.
Main Rotor Features
Each main rotor blade attaches to the hub via two quick-release pins that engage steel mounting lugs. A third pin secures the lead-lag damper. The pins use a spindle and collet system with an over-centring lock lever. The manufacturer stated centrifugal loads on the pin in flight exceed 19,000 lbf.
Detailed Helicopter Examination
Four of the five main rotor blades failed near the blade root at identical span-wise stations. Their lead-lag damper attachments also failed. The fifth blade had a missing forward attachment pin; the lugs were undamaged. The blade cuff rotated back about the rear pin, and the damper attachment was destroyed. The leading-edge tension element wrapped around the rotor mast. An extensive search of the accident site and surrounding area using metal detectors did not locate the missing pin or its parts. Flight path analysis using GPS and radar data identified a possible origin area near the passing airliner, but the pin was not found. No other mechanical anomalies were discovered in the aircraft's controls or systems.