I use both of them Peter.
I asked what types. Perhaps you were flying with ones which gave you a lot of trouble. What do you fly?
Is this a p#ssing competition?
Why do you interpret my question as such? It was a straight question.
How many vac failures or alternator failures have you had?
Zero.
You fly IFR at high altitude (for a light aircraft) - do you have 2 vac pumps on the TB, or indeed a backup alternator? If not, why not? I'm sure a backups could be fitted, especially as its an N reg you own.
I deal with this issue by making sure the stuff I have is in good condition, and having other backups.
The vac pump gets changed at every 2nd annual i.e. every ~250hrs of airborne time.
The alternator gets slip rings and bearings inspected and gets new brushes at every annual. The current one is ~500hrs old and will probably be changed in a year's time.
Common sense dictates if your going to fly solid IFR you would not let these items go on until failure. Prevention is better than cure don't you think? After all, as you state, being an owner is the only way you can fly a plane that's maintained to a high standard.
You are being disingenuous.
You picked two items on which life limits (which would not be mandatory on Part 91 but possibly are under EASA) are far too long, for sensible risk management, and also both items are relatively cheap. A vac pump is a few hundred bucks. If one has any engine work done in the USA it is completely normal to just fit all new accessories like that, always.
What argument would you make for things like seat belts which can be inspected easily and thus life limits make no sense?
Or perhaps Teflon oil hoses, which have no engineering/technical support for life limits, which are operated at about 1/10 of their continuous working rate pressure, yet which are generally lifed under EASA.
That is why I wrote earlier that ownership gives you both options: do it well, or hang yourself.
I'm not saying replace/inspect every 2 years, don't get me wrong. I certainly wouldn't wait until failure however on a 10 year old aircraft though.
See above. A vac pump costs nothing, relatively speaking.
What I could add is that the bit the vac pump drives, typically a KI256 or similar, is likely to fail as often as the pump, but costs about 20x as much. Tell me what you do about that? The KFC225 STC mandates a KI256 (or some ludicrous alternatives).
An electric backup vac pump doesn't help with that, because if the AI goes, so does (on Honeywell systems) the autopilot, which is just what you want
I've had one KI256 last 200hrs, another 700hrs.
Two alternators would be a huge mod for a TB20. Even in the USA, nobody did that
AFAIK despite it possibly facilitating a FIKI certification. One could fit a small vac pump drive alternator, but it would have to be at least a PMAd part, and what will you drive with it? An electric AI? That would be nice but it's a pretty significant-paperwork project. You cannot drive "electronic" avionics from such an alternator unless you have a battery also, unless it is the GAMI one which is not even PMAd. Also the chances of a vac failure or a vac AI failure
and a general electric failure is miniscule (two independent systems).
Anyway, you did very well to read through that 100k word essay
