Case: BF-AV-20260608-002  //  ATA --

CFM56-5B Fuel Pump Overhaul and Remanufacturing

During a routine inspection of a CFM56-5B engine on an Airbus A320-200, uncommanded fuel flow fluctuations and ECAM alerts indicated potential fuel pump issues. The engine had 14,250 flight hours and 8,100 cycles since the last overhaul.

FAILURE MODEThe failure was characterized by severe abrasive wear on the high-pressure stage gear faces and micro-scoring on the carbon-matrix thrust plates. The fuel pump inlet screen was clogged with carbonaceous particles and organic sediment, causing fuel flow restriction and cavitation.
DOWNTIME14 days
COST ESTIMATE45000
ROOT CAUSEThe root cause of the failure was identified as particulate contamination from fuel storage tanks, leading to restricted fuel flow, cavitation, and subsequent pitting erosion within the pump.

DISASSEMBLY AND DEFECT INSPECTION

Upon disassembly of the main engine-driven fuel pump, severe abrasive wear and micro-scoring were observed on the high-pressure stage gear faces and carbon-matrix thrust plates. The inlet screen was heavily contaminated with carbonaceous particles and organic sediment, leading to partial fuel flow restriction. This restriction caused cavitation within the low-pressure impeller housing, resulting in localized pitting erosion and reduced volumetric efficiency. Dimensional checks confirmed deviations from design clearances, necessitating comprehensive remanufacturing.

AEROSPACE COMPONENT REMANUFACTURING

The remanufacturing process followed the Component Maintenance Manual (CMM) guidelines. Precision grinding was employed to restore the pump housing surfaces, while electro-chemical nickel plating was used to re-establish internal design clearances. The internal gear set, carbon bearings, and contaminated filter element were replaced. These measures were taken to restore the pump's structural integrity and operational efficiency, ensuring compliance with regulatory standards.

REASSEMBLY, TEST AND RETURN TO SERVICE

Following the remanufacturing process, the fuel pump assembly was reassembled and subjected to dynamic flow testing and calibration on a hydro-mechanical test bench. This testing verified the pump's pressure margins and operational efficiency. The assembly met all EASA airworthiness directives and was released with an EASA Form 1, confirming its readiness for return to service. The process ensured restored functionality and extended service life.

Prevention

To prevent recurrence, regular inspection of fuel storage systems and adherence to applicable airworthiness directives are recommended. Compliance with OEM service bulletins for fuel system maintenance is essential.

Measurable Results

  • technical status Airworthiness verified and restored
  • efficiency gain Restored volumetric efficiency and pressure margins
  • downtime optimization Significant TAT savings compared to full replacement
  • class approval Released with EASA Form 1
  • service life extension Extended to next scheduled overhaul
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