Q: Which Dry Air Pump is correct for installation on my aircraft?
refer to the application chart on the dry air pump page to find
the correct pump for your aircraft. If you or your mechanic will supply us with
the aircraft make, model and engine type, we will be happy to provide you with
the applicable pump for your aircraft (call 1-800-822-3200 or e-mail firstname.lastname@example.org).
Q: Is an overhauled Dry Air Pump as good as a new pump?
A: We can only speak for our own overhauled pumps
since we have no control over the quality of other overhaul shops. Before Aero
Accessories, Inc. offered an overhauled pump, we spent more than a year in
research and testing to determine what was required to produce a quality
overhauled pump which would last as long as a new pump producing the vacuum or
pressure required for aircraft application. In 1984 Aero Accessories, Inc. had
its overhaul process specification approved by the FAA and began offering quality
overhauled vacuum pumps to general aviation. We take great pride in our state
of the art overhaul facility, and produce the best overhauled pump on the
market today. Over the years we have acquired FAA-PMA's for all component parts
of the Dry Air Pumps, and have supplied replacement parts to all overhaulers
Q: When I start my engine the
vacuum gauge reads zero vacuum, but as the engine RPM increases, the gauge will
indicate vacuum. What causes this?
A: The carbon
vanes inside the pump are sticking in rotor slots. Oil or solvent has entered
the pump either from a bad oil seal in the engine case at the pump mounting
area, or from pressure washing the engine with an oil-based solvent (spraying
directly on the pump). The oil or solvent will work its way up into the pump
through the drive end, mixing with graphite dust and turning into a paste like
A Dry Air Pump is just that: DRY. As the carbon rotor and vanes wear, they
produce graphite dust which lubricates moving internal parts of the pump. When
oil or solvent mixes with this graphite dust, it keeps vanes from moving freely
in their slots and they stick. At low engine RPM, the vanes are recessed in
their slots and create no vacuum, but as engine RPM increases, centrifugal
force slings the vanes out, allowing them to grab air and create vacuum. Once a
pump has become contaminated, its life expectancy is extremely short. The cause
of pump contamination should be determined and corrected and the pump should be
replaced as soon as possible.
Q: What procedures should be taken when replacing a failed pump?
A: (1) A correctly functioning pump
creates a vacuum in the system lines, so when the pump fails (due to wear or
from FOD which has entered pump) the carbon rotor and vanes break into very
fine pieces which can be sucked back up into the inlet hose. It is very
important to remove the inlet and outlet hoses from the aircraft and clean them
out thoroughly, making sure to remove all particles. It is imperative to clean
the entire system after a pump failure. By doing so you will eliminate the
chance of premature failure by your new replacement pump as a result of carbon
FOD from a previously failed pump entering your new system.
(2) After you have installed the new replacement pump, check and make sure the
aircraft vacuum system is working properly. A faulty regulator , dirty vacuum
pump filter, or a crimped or partially collapsed hose which causes a
restriction in the system can force to pump to work harder, causing premature
(3) If your aircraft engine is high time, go ahead and replace the oil seal in
engine case where the pump mounts. The area could be dry now, but the seal
could start leaking in just a few hours causing oil contamination in your
vacuum pump, making it inoperable. Less than $10 dollars spent here could save
you hundreds of dollars later.
Q: I frequently need to replace my Dry Air Pump. What could be
A: 1. Check your hoses to make certain that they
are not collapsed or kinked.
2. Replace the system filter(s). A dirty or clogged filter will cause the pump
to work significantly harder than normal and could cause premature failure.
3. Make sure that you have the correct pump installed on your aircraft.
4. Make sure that no oil contamination is entering the pump.