I am impelled to respond to the correspondence in January’s
Pilot and Ed Lennox’s rant about persons in close proximity to propellers on piston engined aircraft. I have to side with Simon Noble on this matter as it is serious – particularly as Pilot is certainly read by many young and new pilots who may not realise that propellers are definitely to be treated with care and respect at all times.
The very nature of aircraft magnetos makes them prone to the possibility of being unexpectedly activated because they are ‘live’ at all times except when earthed by the ‘P’ lead through the ignition switches in the cockpit. This means that if the switches are left on by the pilot at the completion of the flight (a very common occurrence due to the engine being stopped with the idle cut-off) there is a possibility of the engine firing if the propeller is moved, particularly if one or both magnetos are fitted with impulse units. The other possibility is of one of the earth leads becoming detached for some unexpected reason, such as vibration or sometimes the electrical leads being inadvertently stressed during maintenance leading to possible detachment later. For safety reasons you should check for a ‘dead-cut’ on both magnetos before and after flight to detect a detached earth (P) lead.
Whenever handling a propeller always treat it as live. And when accompanying non-aviation adults and particularly children keep them away from propellers. There are other problems associated with coil ignition on aircraft engines but enough is enough and safety can be maintained by the ‘do not touch’ habit by pilots as well as passengers except when necessary for pilots during flight operations.
What is my authority for this opinion? Well over fifty years as a licenced aircraft maintenance engineer and private pilot on single and multi-engined aircraft, although I am now retired. Colin Ford, Atherton While Colin Ford gives sound reason for handling propellers with care, I am not sure pictures of pilots posed in close proximity to them – almost a tradition in aviation – really do encourage anyone to do anything daft – Ed