Inspection Of Hydraulic Tube Assembly Necessary

Editor's Note: The FAA has issued an Emergency AD for the Premier 1 business jet, after the agency received reports of four failures of a hydraulic tube assembly on the aircraft's left engine. Each failure resulted in an in-flight loss of hydraulic fluid.

Below is an edited summary of the FAA's statements on the AD. ANN strongly encourages our readers affected by this AD to take the time to read the entire document, accessed via the FMI link at the bottom of this story.

The FAA received reports of four failures of the part number (P/N) 390-580035-0001 hydraulic tube assembly located on the left engine assembly of Raytheon Model 390 airplanes. The failures resulted in in-flight loss of hydraulic fluid. The tube is installed between the hydraulic pump and the hydraulic pulsation damper and carries hydraulic pump output pressure.

The latest failure occurred on an airplane with 83 hours time-in-service on the hydraulic tube assembly. Failure of the hydraulic tube assembly and consequent leaking of hydraulic fluid could result in loss of hydraulic system functions and risk of fire because of flammable fluid leakage in the engine nacelle. This failure could lead to loss of control of the airplane.

We have evaluated all information related to this subject and identified an unsafe condition that is likely to exist or develop on other Raytheon Aircraft Company 390 airplanes of the same type design. Therefore, we are issuing this AD to prevent failure of the hydraulic tube assembly and consequent leaking of hydraulic fluid. This failure could result in loss of hydraulic system functions and risk of fire because of flammable fluid leakage in the engine nacelle and lead to loss of control of the airplane.

This AD requires operators to:

• inspect the hydraulic tube assembly (P/N 390-580035-0001 or P/N 390-580035-0005) and the clamp (P/N MS21919WCJ6 or P/N MS21919WCJ7) (or FAA-approved equivalent part numbers), as specified in the service information.;
• replace the clamp at each inspection;
• replace the hydraulic tube assembly immediately if any of the problems identified in the service bulletin are found; and
• report the results of each inspection or replacement to the FAA.

FMI: Read The Full AD (pdf)