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Airworthiness FAA Concern Sheet Date: February 13, 2008 Anthony Flores Aerospace Engineer Mechanical Systems & Propulsion, ACE-116W Wichita Aircraft Certification Office 1801 Airport Rd., Room 100 Wichita, KS 67209 316-946-4174, anthony.flores@faa.gov FAA Description of Airworthiness Concern Make, Model, Series, Serial No.: Hawker Beechcraft Corporation (HBC), Model 390 Premier I, RB-4 through RB-224 Reason for Airworthiness Concern: Loss of hydraulic fluid The FAA is aware of potentially unsafe conditions regarding the hydraulic system on Hawker Beechcraft Model 390 Premier I, RB-4 through RB-224. Some Model 390 airplanes that have previously complied with MSB 29-3800 have experienced a loss of hydraulic fluid due to improper installation of the elbow fittings connected to the engine hydraulic pump output port. In each case, the root cause of these hydraulic fluid losses was determined to be improper installation of the MS21908 elbow used between the hydraulic pump and the hose installed by MSB 29-3800. During installation of the elbow, the MS28778 preformed packing was installed on the fitting threads, causing the fitting threads to damage the preformed packing when the fitting was tightened.
During the root cause determination of hydraulic fluid loss issues in the engine compartment, a system non-compliance with 14 CFR Part
23.1189(a)(1)(5) was discovered. The regulations require that each engine installation must have the means to shut-off or prevent the flow hazardous quantities of flammable liquids into the engine compartment. However, there are no check valves installed in the case drain lines.
The installation of check valves would allow flow from the hydraulic pump case drain lines to the reservoir and prevent flow back through the hydraulic pump case drain lines, reducing the volume of hydraulic fluid loss into the engine compartment in the event of a leak in the left or right engine hydraulic system. The loss of hydraulic fluid can result in the loss of the airplane hydraulic system pressure, and the subsequent loss of hydraulic system functions including gear extension/retraction, spoiler functions, and anti-skid braking system actuation.
Reducing the volume of hydraulic fluid loss, may also help retain some of the system functions in the event of a hydraulic leak in the engine compartment.
Request for Information:
Because the FAA is considering airworthiness action on these airplanes, we are soliciting additional information or comments. Please send your comments to the above E-mail address.
This Airworthiness Concern Sheet (ACS) is intended as a means for FAA Aviation Safety Engineers to coordinate airworthiness concerns with aircraft owner/operators through associations and type clubs. At this time, the FAA has not made a determination on what type of corrective action (if any) should be taken. The resolution of this airworthiness concern could involve an AD action or an SAIB, or the FAA could determine that no action is needed at this time. The FAA's final determination will depend in part on the information received in response to this ACS.
The FAA endorses dissemination of this technical information to all manufacturers and requests association and type clubs comments.
Attachments: *SDR(s) *A/IDSX *SL(s) *SAIB *FAASR/*NTSBSR *AD[ *AMOC *RAL Notification: FAA AOPA X EAA Type Club TC Holder Other:
Response Requested: Emergency (10 days) Alert (30 days) Information (90 days) (Space Bar Adds "X" to Check Boxes)
AIRCRAFT OWNERS AND PILOTS ASSOCIATION AOPA 421 Aviation Way • Frederick, MD 21701-4798 Telephone (301) 695-2000 • FAX (301) 695-2375 www.aopo.org February 25, 2008 Jose Flores Senior Electrical/Avionics Engineer Wichita ACO 1801 Airport Road Wichita, KS 67209 RE: Airworthiness Concern Sheet - Beechcraft-HydraulicFluid-ACS Dear Mr.Flores:
This letter is to acknowledge receipt of your Airworthiness Concern Sheet (ACS) on Beechcraft- HydraulicFluid-ACS dated February 13, 2008. AOPA distributed the ACS to appropriate aircraft type clubs for their input.
AOPA understands the importance of the speedy processing of airworthiness concerns and appreciates your efforts to solicit input from industry before proceeding with airworthiness action. AOPA has no comments regarding this particular concern.
Thank you for your time and consideration, and we look forward to working with you again on future Airworthiness Concerns.
Sincerely, Leisha Bell Regulatory and Certification Policy