Tachometer problem

[Westerhuis]

Hello

I have been working on my instrument panel and as such taken my panel out. To make that possible I had to disconnect the (mechanical) tachometer.

After putting everything back together I noticed an issue with the tachometer and that is that the hour meter on there seems to be registering around 1 hour for 10 minutes that the engine has been running e.g. the engine meter is running fast..

Although it still seems to be showing me to correct revs. I guess I can't be sure.

Its a mechanical tachometer that is connected to a 1200 CC Rectimo (VW Beetle) engine fitted in a Fournier RF-3.

Does anyone have any idea what this could be / experienced a similar issue?

Thanks!

Rogier

[rfmorton]

Hi Roger,

You have hit the 'average tacho' problem! Mechanical tachos are designed to log hours at an 'average' (cruise) rpm, which is usually about 2400 to tie in with Continental / Lycoming cruise rpm's. When used with a VW, the cruise rpm will be much higher, typically 2800 rpm, thus your tacho hours will be running fast. There is nothing you can do about it except to fit a Hobbs meter running from either the alternator if fitted, or a battery connected to the master or magneto switch if engine electrics are not available. There is no adjustment fitted to the mechanical tacho.

I take it the tacho is an 'AC' manufacture or similar? Hope this helps.

Robin Morton
LAA 000144