Dry Air Pump Questions and Answers:

Q: Which Dry Air Pump is correct for installation on my aircraft?

A: When selection a dry air pump for installation refer to your aircraft parts manual. For additional reference please refer to the Application Guide on the Dry Air Pumps page to find the correct pump(s) for the aircraft. Locate the aircraft make, model and engine to view the applicable pump(s) for your aircraft (call 1-800-527-2726 or use our contact us page).


Q: Which new Dry Air Pumps replace the 211CC or 212CW?

A: The Rapco new RAP215CC is the approved FAA-PMA replacement for either the superseded 211CC or the 215CC. In the same respect the RAPCO new RAP216CW is an approved FAA-PMA replacement for either the superseded 212CW or the 216CW. The Rapco overhauled 215CC is a direct replacement for the superseded 211CC or 215CC. The Rapco overhauled 216CW is a direct replacement for the superseded 212CW or 216CW. When selecting a pump for installation please consult your aircraft parts manual.


Q: Which pump do I choose, new or overhauled?

A: New models are FAA-PMA approved as a direct replacement part. Overhauled pumps are produced under our FAA process specification and come with a FAA form 8130-3. All new pumps have an inspection port for monitoring vane wear which increases safety by helping to determine when replacement is needed. All new RAPCO dry air pumps have an oil seal on the main shaft to help prevent oil from entering and damaging the pump. For convenience, RAPCO includes a mounting gasket and vane measuring caliper with every new pump. New pumps also come with cooling fins that reduce operating temperatures and helps to extend pump life. In addition, there is no core charge when purchasing a new RAPCO dry air pump. All RAPCO dry air pumps, new or overhauled, are internally coated with a special Mil-Spec hard lube coating that reduces friction and wear. The carbon rotors inside our new and overhauled pumps have also been improved by chamfering the leading edges of the vane slots. This helps to reduce the chance of failure due to foreign object damage. Dry air pumps can be used for vacuum or pressure system applications. RAPCO quality dry air pumps offer exceptional value and are backed by our warranty.


Q: With my engine at idle, the vacuum gauge reads zero, but as the engine RPM is increased, the gauge will indicate vacuum. What causes this?

A: The cause for this symptom is most likely the carbon vanes sticking in the rotor slots due to an oil or solvent entering the pump. A leaking (Garlock) oil seal in the accessory drive case can cause this as well as the engine being washed with an oil based solvent without having the pump completely covered. Both of these fluids will work their way into the pump, mix with the carbon dust, and turn into a paste like substance.

Dry Air Pumps MUST remain DRY or their life expectancy will be cut extremely short. Inside each pump is a carbon rotor with vanes inside its slots. Centrifugal force slings these vanes out and against the Mil-Spec coated cavity walls moving air and creating vacuum or pressure. During this process, graphite dust is created as the vanes wear and helps keep everything in the pump moving freely. That is until the graphite dust is introduced to a fluid or moisture that creates the paste like substance, sticks the vanes in the slots and does not allow them to move freely and push or pull air until higher RPMS puts greater force on them to do so.


Q: What procedure should be taken when replacing a failed pump?

A: Each RAPCO pump comes with a Dry Air Pump Removal & Installation Instructions and Tips manual. If you no longer have that manual, please click on the link above to view it.


Q: What could be causing my pump to frequently fail?

A: 1) Check the Dry Air Pump Application Guide to be sure the correct pump is installed on the aircraft.

2) Check all hoses to be sure that they are not dry rotted, crimped, or kinked causing excess strain on the pump or contributing to a FOD entering the pump.

3) Make sure that the (Garlock) oil seal in the accessory drive case hasn't failed and is allowing oil to contaminate the pump

4) Replace all pneumatic system filters, as a dirty or clogged filter will make the pump work significantly harder which will cause premature failure.

5) Aircraft equipped with de-ice equipment should have their de-ice control valves checked for proper operation. Stuck de-ice control valves cause great strain on pumps making them work extremely harder than normal.


Q: My shear coupler has sheared, but is it possible my pump is still good?

A: The life of the urethane shear coupler can be shortened by age, number of cycles, heat, oil, and solvents. More information regarding the replacement of the shear coupler can be found in our Service Letter RASL-008.

It should NOT be assumed that your pump is still in good working order after the shear coupler has sheared. First check to see if you can still turn the pump by hand; if so then follow the advice in the Dry Air Pump Removal & Instructions Tips regarding the inspection of your pneumatic system components.


Q: What is the difference between the RAP215CC and the RAP215CC-9 or 211CC and 211CC-9 Dry Air Pump?

A: The RAP215CC-9 (211CC-9) dry air pump was designed to mount vertically on the accessory pad at the bottom of a Continental O-200 engine. This location is susceptible to oil contamination which can ruin a dry air pump.  The 211CC-9 pump is an attempt to deal with the contamination issue by using a slinger ring on the drive shaft of the pump to throw off any oil that might happen to drip down from the engine onto the shaft. The oil is slung into a channel with a drain hole to try to keep it away from the shaft. It helps although if the oil leak is not quickly resolved the pump will soon fail to operate.  There are also a few other applications in which aircraft manufacturers have specified that the -6 pump go on other engines even though it was mounted horizontally. On new RAPCO pumps we use a proprietary oil seal on the drive shaft instead of the slinger ring to address this issue. In addition to the RAP215CC-9 this oil seal is included in all RAPCO new dry air pumps.



Vacuum Regulator Questions and Answers:

Q: Is it possible that my vacuum regulator is not adjusted properly for my particular application?

A: Regulators come factory preset, however they occasionally need initial adjustments depending on the particular installation. Instructions on how to adjust the regulator can be found here: Regulator Adjustment


Brake Disc and Lining Question and Answers:

Q: Why are my brakes dragging, squealing, pulsating, or wearing my linings unevenly?

A: To best determine the cause of any of the above concerns, please see our Brake Troubleshooting Tips.


Q: How do I determine if I have organic or metallic linings?

A: Organic linings are installed only using rivets and have a built in wear indicator.

Metallic linings have a steel carrier plate that is part of the lining and uses mounting pins for installation.

To view our brake linings, please see our Brake Lining Product Guide.


Q: How do I break in my brake linings or discs properly?

A: For the proper break in procedure of either organic or metallic linings, please see Service Letter RASL-004.


If you still have additional questions, please feel free to call 1-800-527-2726 or use our contact us page.

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