PA-31 Navajo/Chieftan/Mojave/T1040
Flight Crew Air Transport Pilot (ATP)
Aircraft Equipment Problem Less Severe
Flight Crew Diverted; Flight Crew Landed As Precaution; General Maintenance Action
Aircraft
R.H. pneumatic pump warning annunciator came on and remained on during the entire flight. I pushed the annunciator to see if that would reset it; but the light would not go out. I contacted dispatch from the air and the dispatcher discussed the situation with maintenance. After that discussion; dispatch asked that I return directly to ZZZ; which I did without any issues. During the flight all pressure-driven flight instruments operated normally and the pressure was normal. De-ice boots were not needed during this flight. Maintenance removed and replaced the R.H. pneumatic pump and told me that the shaft in the old pump had sheared. It was a hard pump failure. I don't know the maintenance and performance history of the pneumatic pumps but if they are like the vacuum pumps typically used on smaller GA airplanes; they can be problematic and prone to failure. Some owners/operators replace vacuum pumps prophylactically at 500 hours time in service.
PA-31 pilot reported the right pneumatic pump failed; so he diverted after consulting Dispatch.