Piper Aztec PA23 250 - Service Difficulty Alert

AL 2009-03
19 May 2009

Emergency Gear Extension Control System

Following a normal take-off and landing gear retraction, hydraulic fluid was noted leaking from the manual hydraulic hand pump.  Attempts to extend the landing gear with standard system or manual hand pump failed due to a complete lost of hydraulic fluid.  Emergency gear extension control (EGEC) was deployed but also failed. Fortunately, a crewmember was able to gain access to the (pneumatic) priority valve (Part Number 492-097) pin and pulled it using extreme force. Once the pin was removed, the landing gear extended with normal indications and a successful landing was carried out.

Further investigation of the EGEC system revealed the cables to priority sequence valve (that activates the CO2 bottle) had been improperly rigged. Upon review of the Piper Maintenance Manual, it was noted that there were no requirements to inspect the EGEC system at a regular interval or after being used.

Piper Aircraft Corporation previously issued Service Bulletin (SB) No. 564, dated 25 April 1977, to carry out an inspection of the EGEC system at next scheduled inspection only.

Piper Aircraft will be updating the Service Manual/Maintenance Manual as part of the recurring 100-hour inspection interval.  This revision will be released before year-end.

In the interim, Transport Canada Civil Aviation (TCCA) recommends operators to:

  • Inspect the system at next scheduled inspection or maintenance activity as per SB 564
  • Incorporate the inspection of the system into their maintenance schedule program, hourly or annually
  • Inspect system after being used as per SB 564.





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Defects, malfunctions and failures occurring on aeronautical products should be reported to TCCA via CAR 591 Service Difficulty Reporting requirements.

For further information, contact a Transport Canada Center, or Mr. Guy Richard, Continuing Airworthiness, Ottawa at 613-941-7466, facsimile 613-996-9178, or email guy.richard@tc.gc.ca

Derek Ferguson
Acting Chief, Continuing Airworthiness

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