Originally Posted by foxmoth
A good example is again the stall warner, any instructor who cannot recognise an approaching stall without a warner should not really be in the job (and many aircraft do not have a warner of course!), but for a PPL student with only 10-20 hours this may be a different matter.
The fitting of a stall warner is often a certification issue. i.e. the aircraft needed a stall warner to be certified. A reason for this could be a lack of aerodynamic warning or other issues that can be worked round by giving the pilot a clear warning of an approaching stall.
Most pilots inlcuding instructors are not in a position to know why that particular aircraft has a stall warner - was is an essential part of the certification or was it simply something nice to have fitted. Thus if the stall warner is u/s then the aircraft is u/s.
The CAA publish master minimum equipment lists for various aircraft and these can be used to gain approval for an MEL.
Without an MEL, unless the equipment is optional then it has to be fully serviceable for flight.
References include the Type certification data sheet, FAR23 and JAR23 and the Master Minimum Equipment Lists for the particular aircraft.
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Very importantly, a major misconception is that an instructor could fly an aircraft that would not be considered serviceable (safe) for a student or low hours PPL. The pilot experience or skill does not enter into the decision as to if an aircraft is serviceable or not.
If the aircraft is serviceable then every pilot can fly it. If it is not serviceable then no pilot can fly it.
Regards,
DFC