Don Maxwell
Published by MAPA Log Magazine
Volume, 24, Number 4
April 2001

This past week, Airborne issued Service Letter 54B. The subject of the Service Letter, inspection and replacement requirements of their Engine driven clutch operated vacuum pump, has been an ongoing problem with the TLS/Bravo and now the Ovation.

My first encounter with this problem was in 1998. A customer, in for annual, requested a new vacuum pump be installed since it had a little more than 1000 hours, A call to my supplier for a pump revealed that if this pump was going on a Mooney with the clutch operated vacuum pump, it would be free of charge. Seems as though Airborne knew they had problems with the backup pump and by supplying a new pump could buy a little time on the replacement clutch operated pump.

Early TLS/Bravo's did not have a vacuum gauge for the backup system, just a light on the annunciator panel would indicate that the standby vacuum system is working. Not so. The illuminated annunciator is indicating that the field of the electric clutch on the standby vacuum has been energized. This Does not mean the standby vacuum system is working.

Mooney has a retrofit vacuum indicator or you may want to install a separate vacuum gauge if your aircraft is not equipped with one.

Concerned that our standby vacuum might not be working and awaiting our new pump, we checked their operation of the standby system and it did not work. After a call to Airborne, we were referred to Scott Strunk.  Mr. Strunk, 440-248-6215, acknowledged Airborne was aware of the problem and agreed to send us a new standby system, P/N 28C214CW-2 free of charge. The pump was received and installed along with a vacuum indicator for the system. List price for this system at that time was approximately $2,000.00. Today I checked prices on Mooney's web site and the price for this pump was $2,250.00 and none being available.

When I received the new Service Letter today, I called Airborne's tech line to see if they had made an error in the list price for the new and improved replacement pump P/N 28C214CW-4 $12,150! I was referred to Mr. Dave Simpson, 440-248-6313 who not only assured me the price was correct, but that an adapter for the new pump would also need to be purchased for $562.00. Unbelievable, $12,712.00 plus labor for a standby vacuum system that will only be good for six years or 500 aircraft hours. I asked Mr. Simpson if it was the intent of Airborne with this Service Letter to get out of the clutch operated standby vacuum business and he said it was not. In a search for and alternative, I called a friend who is the service manager for a large Piper shop. The Malibu uses a similar system on the early Malibu. Later model Malibu's have two vacuum pumps that operate continuously. He stated that there was an STC underway to replace the clutch operated pumps on early Malibu's to the later style.   When this STC is approved, it may be beneficial to our Mooney owners also.

Other alternatives are an electric AI, or a rear mounted electric standby vacuum such as installed on 231's and 252's (see photo #2) This option, for less than $3,000.00 is more reliable and less expensive. Hope this has been helpful. Any questions check with your local Mooney Service Center for possible alternatives or feel free to call.

Don Maxwell







Don Maxwell