21SN04-354 — Pressure Switch Repair & Overhaul

Component Overview

A pressure switch is an electromechanical sensor that monitors fluid or air pressure and actuates an electrical contact when a preset threshold is crossed, providing system protection, indication, or control signals within the sensors-and-switches domain. A sensing element such as a diaphragm, bellows, or piston deflects against a calibrated spring to open or close contacts at the setpoint, feeding warning, shutdown, or sequencing logic. In service it experiences fatigue and creep of the sensing element shifting calibration, contact erosion, pitting, and oxidation increasing resistance, and spring relaxation altering trip points. Diaphragm rupture, seal leakage, contamination, and corrosion are common failure modes that produce setpoint drift, chatter, or failure to actuate, driving recalibration, contact servicing, seal replacement, and setpoint and continuity verification.

Aircraft Application

Part number 21SN04-354 (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 21SN04-354 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 →

Related Parts

Other pressure switch part numbers we repair — view all Pressure Switch parts →

Frequently Asked Questions