26/08/2011 - Push Rods & Research and other bits

Constructed and painted the aft pushrod for the elevators:

I have bought the std Airflow performance pump and filter a while ago from VANs but recently I spotted this information which is useful.

Airflow Performance Fuel Pump and Filter Information

Thanks to Rob Wright and his conversations with Airflow Performance, Inc. we now have a good bit of information on our boost pumps and filter systems.

Here's the discussion (edited for better flow):

"I'm using your Filter/Pump assembly in an RV-10 and would like to know what if any bypass capability there is if the filter clogs/fails or if the pump fails. Do you also have a schematic or other written literature detailing this? Do you also have any information on the filter?"

The response:
"Your question specifically asks if there is a bypass around the fuel pump. The answer is, there is a swing check valve around the pump that allows free flow to the engine driven fuel pump when the pump is off/clogged/failed. See the attached boost pump manual.

The filter is a non-relieving type. This is a 125 micron pleated stainless filter with a capacity of 180 GPH @ 1 PSID. In 15 years of manufacture of this filter there has not been to date a restriction of fuel due to this filter clogging. That does not mean that it can't happen. We have studied the situation of relieving vs non-relieving filters when being used for a suction filter and determined that having a bypass open at less than .5 PSI would allow more trash to enter the system than it would prevent in normal operation. Flow surge is also a problem for opening a low pressure check valve and this is a suspected problem with reliving filters in other aircraft injection systems. If you install Airflow Performance fuel injection in your aircraft the system is protected by 3 fuel filters. There is the 125 micron filter before the boost pump, a 75 micron filter in the fuel control inlet and a 72 micron filter in the flow divider. Attached is the filter manual. "

Don Rivera
Airflow Performance
111 Airflow Drive
Spartanburg, SC 29306
Phone: 864-576-4512
Fax: 864-576-0201
E-Mail: Airflow2 at bellsouth dot net