Garmin GFC 500 Autopilot on M20J

[rcwagner]

A previous owner in 2009, didn't sump the tanks after the airplane was parked outside all night in a pouring rain.  Engine quit on takeoff, he got it back on the pavement, but went off the end and hit a fence post with one wing.  The inertia bent the tailbone.  It was replaced with an M20L (remember the Porsche Mooney) tail cone.  M20Ls were 28 volts, two batteries.  A bulkhead was moved about an inch to accommodate the new design and higher gross weight.

[bradp]

23 hours ago, rcwagner said:

A previous owner in 2009, didn't sump the tanks after the airplane was parked outside all night in a pouring rain.  Engine quit on takeoff, he got it back on the pavement, but went off the end and hit a fence post with one wing.  The inertia bent the tailbone.  It was replaced with an M20L (remember the Porsche Mooney) tail cone.  M20Ls were 28 volts, two batteries.  A bulkhead was moved about an inch to accommodate the new design and higher gross weight.

Did they have to get a DER for that?

[see_kay]

"I have a KFC150 in my 252 and no vacuum system. (Well technically I still have a vacuum system but it's only connected to my speed brakes) Nothing in my panel is connected to vacuum."

gsxrpilot  - I would be interested to hear whether you were able (allowed) to tie your electric Vac pump to the speed brake switch... I am planning to remove the engine Vac pump so will be in the same situation and would like to only run the electric pump when it is actually needed (ie only when the speed brakes are active)

[carusoam]

Message for @gsxrpilotabove...

-a-

[gsxrpilot]

10 hours ago, see_kay said:

gsxrpilot  - I would be interested to hear whether you were able (allowed) to tie your electric Vac pump to the speed brake switch... I am planning to remove the engine Vac pump so will be in the same situation and would like to only run the electric pump when it is actually needed (ie only when the speed brakes are active)

If I'd thought of that I'd have tried to get it approved. But I ended up removing the electric vac pump and keeping the engine driven pump. As you said, the speed brakes are the only thing connected to it.

[aviatoreb]

4 hours ago, gsxrpilot said:

If I'd thought of that I'd have tried to get it approved. But I ended up removing the electric vac pump and keeping the engine driven pump. As you said, the speed brakes are the only thing connected to it.

Why would that be better?

[gsxrpilot]

3 minutes ago, aviatoreb said:

Why would that be better?

It would have moved the weight to the tail rather than on the engine. Otherwise, it's probably a wash.

[EricJ]

9 minutes ago, aviatoreb said:

Why would that be better?

It also removes another drive item from the accessory case and frees up a pad.    A backup alternator is a candidate to put there, or just leave it open for better access to the rest of the accessory case.   I'd like to get rid of mine just to free up the space back there.

[aviatoreb]

1 hour ago, gsxrpilot said:

It would have moved the weight to the tail rather than on the engine. Otherwise, it's probably a wash.

 

1 hour ago, EricJ said:

It also removes another drive item from the accessory case and frees up a pad.    A backup alternator is a candidate to put there, or just leave it open for better access to the rest of the accessory case.   I'd like to get rid of mine just to free up the space back there.

Ah - thanks both.  On the one hand if I want I have two points to mount accessories and one is open.  So a plane power backup alternator would fit.  But with two batteries I haven't bothered.

I have two batteries in the tail to add extra weight - which is part of the rocket mod - plus 19lbs of dead weight in the tail.  I suppose keeping the electric backup vacuum is the same as removing a piece of lead from the tail, vs removing the electric.

On the other hand, its nice and simple to just have the engine driven vacuum just always on and no need to remember to flick the vacuum on switch before speed brakes.

I could see doing it both ways.  I am leaning to just keeping the engine driving vacuum and removing the electric thing.  But i might change my mind.