B737-800
Flight Crew Instrument; Flight Crew Multiengine; Flight Crew Air Transport Pilot (ATP)
Communication Breakdown; Troubleshooting
Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural Maintenance; Deviation / Discrepancy - Procedural MEL / CDL
General Maintenance Action; General Release Refused / Aircraft Not Accepted; General Flight Cancelled / Delayed
Company Policy; Logbook Entry; MEL; Manuals; Aircraft
Aircraft X has been flying around with chronic hydraulic fluid transfer between system A and B for months. I refused the aircraft due to mis application of MEL 29-XX. It turns out I was correct about the part replaced due to this incorrect MEL. It was not the problem. The part was the system a fluid level sensor. This aircraft has been and continues to fly in revenue service in an unairworthy condition. This aircraft needs to be grounded and positive corrective action taken. By [Maintenance Control] admission; this is a long-time recurring issue. The [maintenance log] as well shows a 'deferral' for 28 days as of today. It's actually been longer than that by my observation. In summation if the above is not sufficient to ground this aircraft; there is no MEL relief for hydraulic fluid transfer between sys A and B and [Maintenance Control] admits this is a 'deferral '. An illegal deferral. This recurring over full condition is also unsafe and violates the placard on the hydraulic fluid reservoirs.
Captain reported refusing aircraft opn multiple occasions because of misapplied MEL and incorrect maintenance procedures.