Q: Are there any Service Bulletins or Service Instructions pertaining to permanently removing a vacuum pump from a Lycoming engine?
I’ve noticed a Plug-Vacuum Pump Drive, P/N LW-10303, is shown in some parts manuals, but is not shown in other parts manuals.
The engine I’m currently servicing is an IO-360-C1C6, installed on a PA-28R-201 (Arrow III), built in 1978. This plane has recently had its two original gyros removed and replaced with dual Garmin GI 275 indicators.
Greg Stockman, A&P/ IA
A: There are no Service Publications covering what you’d like to do Greg, but all is not lost.
There is no problem removing the vacuum pump drive from the engine — and there are actually two options for you.
The first is to remove the vacuum pump, which you have already done, and I assume you installed a gasket and cover plate on the vacuum pump adapter at that time. There is no reason that configuration cannot be used and this will allow a standard vacuum pump to be reinstalled in the future.
You may also remove the entire vacuum pump adapter, gear, and thrust washer and by installing a P/N 8313 gasket, and a P/N 60430 cover plate, plus four each P/N 68593 spacers you are good to go.
My suggestion would be to leave the adapter and gear in the engine and just go with the cover plate. This gives you the option of going back to a dry vacuum pump anytime in the future without having to purchase any parts.
I’d suggest you reference the Lycoming Parts Catalog PC 406-2, Pages 2-13 and 2-14 to confirm exactly what parts are required.
Editor’s Note: See an update to this question and answer here.
Vacuum vacuum system on a lot of aircraft was optional. If it was optional it is not part of the type certificate and can be removed without an STC or field approval from the airframe. The engine is the same way. The parts catalog shows a cover to put in place of the vacuum pump. Any engine that comes from the factory comes with that cover. You will notice however that the gears and shift for the vacuum drive are mandatory.
That’s what I was thinking. It seems to me that removing the gear and thrust button from the engine would be a major alteration.
It would be nice to remove the weight and energy required to spin it. Logically, the change would have a “minor” impact on the engine’s function. But the FAA doesn’t generally deal with logic, only data.
A third option is possible. Since the aircraft seems to be an all electric system, there are after market backup alternator systems that can be installed on the now vacant PTO. If the aircraft is used to fly IMC routinely, it might be wise to have another electrical source besides the battery.
Hi Paul
I’m a proud owner of a Mooney Rocket 305.Now my question:What is the correct TIT setting en route in FL100 and FL 180?
1500,1550,1600 or 1650,always rich of peak.
Greetings from Switzerland
Sandor Faddi
HB-DYB