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Piper Malibu Research Site

I survived the crash............and decided to do some research.

What I found may interest you if you own or fly a Malibu!

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This is N9102V, a 1986 model Piper PA46/310P Malibu.  The aircraft was formerly in the rental fleet of the Epps Air Service -Flight School located at Peachtree-Dekalb Airport in Atlanta, GA. At the time of the crash in December of 1995, it reportedly had accumulated 1920 hours total time with 1789.2 hours on the engine. This time accumulated over a period of approximately 10 years. Inspection of the wreckage and review of the Factory Maintenance and Overhaul Manuals of Piper Aircraft Corporation and Teledyne Continental Motors has narrowed the focus of this research to four areas.

1. The Continental Fuel Injection Manual (Part #X30593A) indicates that the Continental "Rotary Vane" type engine driven fuel pump may develop an internal leak in the pressure side of the pump and discharge fuel through the fuel pump seal bypass drain while the system is under pressure.  Another indicator of  potential fuel pump failure is an unexplained rise in the crankcase level on the engine dipstick. This would indicate bushing and shaft wear at the drive end of the fuel pump and/or an obstructed seal bypass drain line which would allow case pressure to build within the pump housing, causing fuel to bypass the seal and potentially leak into the crankcase.

2. While the Continental Continuous Flow Fuel Injection System is used in a number of other Continental engines, the Malibu version of the fuel pump is unique in that it incorporates an Aneroid Pressure Chamber to sense changes in induction pressure as they occur in the pressure side of the engine intake system. This allows the system to compare atmospheric pressure to manifold pressure and vary the fuel pressure and flow available to the throttle body accordingly. A pressure leak in the aneroid chamber bellows may "fool" the system into believing it is operating at a higher or lower altitude and lead to an "over rich" or "over lean" condition in the fuel system. This condition may result in partial or complete loss of engine power.

3.  There are reports of  Fuel Pump Drive Coupling disengagement. Indications are that some of the shafts are too short. When combined with shoulder wear on the drive end of the fuel pump and shoulder wear to the hex on the crankshaft, drive coupling disengagement is apparently possible. This is addressed in Bulletins MSB95-6 and SB97-13. 

4.  Service Bulletin 95-7 details potential loss of fuel pressure as a result of leakage at the fuel manifold valve. More on this later....

The Continental Parts Manual shows Part #s 646571-1 and 649374-1 fuel pumps as the correct applications for the TSIO520BE, however the manual goes on to say that these units are not field serviceable but must be replaced with a new unit or returned to Continental for overhaul.  The pump replacement cost  at a reported $8,000 to $10,000 is very high. The high cost (possibly due to limited production) combined with customer complaints and service issues apparently led Continental to recently issue  Service Bulletin 97-13 as an alternative.

Click Here to visit the Service Bulletin List as of 6/98.

The consensus among Malibu pilots who have contacted us is that the 2000 hour TBO for the Continental TSIO520BE series engine may be acceptable.  However the repair histories shared with us by pilots and mechanics familiar with the Malibu indicate that a 5 year or 1000 hour service level might be more appropriate for the fuel pump and the aneroid chamber.

Do you have information about the Malibu and its Engine or Subsystems you would like to share with other pilots? Visit Contact Us and make your information available to other pilots.

Fuel Pump Image

Watch for frequent information updates on the site.......

Thanks for your help!

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