Maintenance Airframe; Maintenance Powerplant
Confusion; Situational Awareness
Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Published Material / Policy
Flight Crew Returned To Gate; General Flight Cancelled / Delayed
Chart Or Publication; Manuals; Human Factors; Aircraft
I was assigned the Anti-Skid Control Valve union filter cleaning Task Card on a Raytheon Beech jet 400 aircraft while working in the hangar for Air Carrier X at ZZZ. I performed the task in accordance with the Hawker 400/400A Maintenance Manual (M/M) 32-40-00. When I was reinstalling the lines I mixed up the aft hydraulic pressure lines to the valve. The lines were not hard to install in this way and the installation seemed right to me. I had my Lead Mechanic buy-back [verify] the work. We ended up job stopping the task; with the Brake Bleeding and Anti-Skid Control Check still needing to be accomplished. The lines still got mixed up even though the lines were tagged. I could have taken a picture of the valve before I started the task. This would probably have prevented the lines from being installed wrong because I would have referenced the Maintenance Manual (M/M) and the picture. The Anti-Skid Brake System Check in the Maintenance Manual says to push both brakes at the same time during the Check. A revision to the manual that would require each brake to be checked individually and verify proper operation probably would have caught the problem in maintenance. The Repair Station could adopt a policy of requiring a run/taxi after brake maintenance procedures. This would have caught the problem while it was still in maintenance. Graveyard shift. Gate-turn back.
I; Mechanic Y; received a [shift] turnover from Mechanic X for a BE400A aircraft. Per Mechanic X; he removed the Power Brake Anti-Skid Control Valve from the aircraft and performed filter maintenance earlier that evening. He stated removal was necessary for ease of maintenance and there was difficulty of component during reinstallation. I then asked if the valve needed to be leak checked. His answer was it had been completed. Thus; the Power Brake System already had been operated via hydraulic mule. Furthermore more instruction was stated from Mechanic X. It included a brake bleeding procedure remaining in the task due to the lack of O-rings in the Parts Department. The task stated 'Refer to MANUAL BRAKE BLEEDING' procedure. Mechanic X then went onto explain that the 'MANUAL BRAKE BLEEDING' was incorrect; and for us to perform the 'POWER BRAKE BLEEDING'. Mechanic X stated it was a common practice at the Aircraft Service Centers and [our] Air Carrier at ZZZ to perform the 'POWER BRAKE BLEEDING'. I then accepted the work. As we began working the 'POWER BRAKE BLEEDING'; we noticed the brake bleed cart [was] already connected to the aircraft brake assemblies by Base Technicians. This eliminated us from actually connecting the hose assemblies to the brakes. We went on to performing the 'POWER BRAKE BLEEDING' as stated during the turnover. During the brake bleed; I and another Technician Z opened the # 3 and # 4 bleed cart valves and examined the fluid for any air in the hydraulic fluid. We never saw any entrapped air during the bleed process. As we continued the # 3 and # 4 valves were shut off. I then asked the Brake Pedal Operator about the brake pedals being firm and he stated they felt good. The brakes also showed good and equal pressures as they were operated several more cycles. We then went on to perform a successful ANTI-SKID FUNCTIONAL TEST. Finally; the jobs were both completed in the afternoon when the O-rings were received and the brake bleed cart removed.After learning about the event; several items could be open for discussion so further or similar events do not take place: 1) The Brake Bleed Cart should have been installed correctly. EG: The # 1 Brake bleed hose and gauge should have been connected to the Left Main Brake Assembly and the # 3 Brake bleed hose and gauge should have been connected to the Right Main Brake Assembly. 2) The incorrectly installed hydraulic lines and valve connections should be permanently marked to ease the proper installation process. 3) The oncoming shift should have inspected the brake bleed equipment for proper installation prior to use. 4) If the brake cart was not already set up for use; our crew may have used vinyl tubing and drip pans to perform the brake bleed method; thus we would have physically seen the fluid directly flowing out the brake assemblies; allowing us to discover the incorrect valve installation. 5) More complete training needs to be accomplished for all team members on all multiple aircraft types for more proficient skills and understanding.
Three Aircraft Maintenance Technicians report about their involvement with a power brake anti-skid control valve filter change and power brake bleeding procedure that resulted in a gate return of a BE-400A aircraft. Flight crew noted the left pedal controlled the right pedal and the right pedal controlled the left pedal.