21SN04-298A — Scavenge Filter Pressure Switch Repair & Overhaul

Component Overview

A scavenge filter pressure switch is an electromechanical sensing device in the engine oil scavenge circuit that monitors pressure, or differential pressure across the scavenge filter, and provides an electrical signal or cockpit indication when the value crosses a set threshold, warning of filter clogging or abnormal scavenge pressure. Internally a diaphragm, bellows, or piston acted on by oil pressure actuates electrical contacts at a calibrated setpoint. Operating in a hot, vibratory, fluid-wetted environment, typical degradation includes setpoint drift from spring relaxation or diaphragm fatigue, contact pitting and erosion, internal and external leakage past seals, corrosion and contamination affecting the sensing element, and connector or wiring deterioration. These conditions drive setpoint verification, leak and continuity testing, recalibration, and overhaul to restore accurate switching.

Aircraft Application

Part number 21SN04-298A (Scavenge Filter Pressure Switch) is installed on the Pratt & Whitney PW2000/4000. QTC supports operators and MROs servicing this platform with certified repair and overhaul.

Our Repair Capability

QTC repairs and overhauls 21SN04-298A to the original manufacturer's specifications under our FAA and EASA Part 145 approvals. Our team — including former OEM sensors & switches engineers — performs teardown, inspection, cleaning, component replacement, functional testing, and certification, returning a serviceable unit with the appropriate airworthiness release. We also develop repairs for rejected and beyond-economic-repair (BER) hardware.

View Differential Pressure Switches capability →

Frequently Asked Questions