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