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Red Arrows Pilot May Have Been Killed Due To An Over Tightened Shackle Nut
By Jim Douglas

January 14, 2014 - Back on November 8, 2011 Lt Sean Cunningham a pilot with the Red Arrows, the Royal Air Force Aerobatic Team based at RAF Scampton, England was killed when he was ejected from his single-engine BAE Hawk T1 advanced jet trainer aircraft while he was performing a cockpit preflight check while on the ground at an at RAF airfield Scampton. 

Cunningham was ejected from his aircraft through a smoke filled canopy 300 feet into the air while still seatbelted to his pilot seat. Cunningham’s parachute failed to open resulting in fatal injuries when he hit the ground. 

Near by ground crew had to duck for cover when the canopy blew open as Perspex (a transparent thermoplastic, often used as a lightweight or shatter-resistant alternative to glass) shattered across the ground. 

Early speculations suggested Cunningham failed to deploy his parachute when he was ejected from his aircraft as a result from taking a flu medication the night before the flight called Night Nurse which some believed the side effects affected his judgment. 

Night Nurse is a popular cold and flu medication in the UK. Night Nurse contains three main ingredients which work together to relieve cold and flu type symptoms which allow a sick person get a restful night sleep. 

- Paracetamol is a pain killer

- Promethazine is an antihistamine which works by blocking the effects of histamine and suppresses the urge to cough, and also dries secretions in the nose. It causes drowsiness which is helpful for night time coughs.

- Dextromethorphan suppresses the urge to cough and relieves dry, tickly coughs.



However, testimony at an inquest into the cause of the accident may shed light into the failure of the parachute not being deployed. It is now believed that an over tightened “shackle nut” disabled the parachute from being opened. On Monday the inquest heard testimony that indicated Cunningham would have survived if his parachute worked and the failure of the shoot from being deployed was most likely due to a maintenance worker that over tightening a bolt in the ejector seat and that RAF ground who serviced the aircraft were unaware that a “shackle bolt” in the rear of the chair could, if over- tightened, cause the seat to malfunction. 

Testimony was also given that the BAE manufacturer’s maintenance instructions failed to mention the danger in over tightening the bolt. When an ejection seat of the BAE Hawk T1 is deployed, a small parachute called a drogue parachute is first to deploy to provide control and stability and then the larger parachute is deployed. In order for this to work a piston inside the seat forces a scissor shackle to release the drogue shackle from its jaws but in order the shackles to separate the nut and bolt through both of them must not be over tightened. 

A maintenance worker testified before the court he understood the shackle nut and bolt should be tightened with two threads showing he further stated he was unaware at the time that over tightening could prevent the parachute from opening. Another worker stated his understanding at the time was to tighten the nut and bolt to one and a half to two turns. An attorney for one of the workers asked his client “Had it occurred to you that over tightening of the nut and bolt in the drogue might have the effect of causing a pinching of it with the scissor shackle so that it did not work in operation?” His client replied “I wasn’t.”

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