778686-4 — High Pressure Shutoff Valve Repair & Overhaul

Component Overview

A high-pressure shut-off valve is a pneumatic isolation valve in the air-management system that controls a high-pressure air or bleed line, providing positive open and closed states to start, stop, or isolate flow for normal operation and protection. It is generally a butterfly or poppet element actuated by a pneumatic or solenoid-piloted mechanism with spring return, designed to seal reliably under high pressure and temperature. Its primary function is dependable shutoff and isolation of high-pressure air. In service it suffers seat and seal wear and erosion, shaft and bearing wear, actuator and spring fatigue, solenoid or pilot-valve faults, and contamination or carbon buildup, all of which produce leakage, sticking, or sluggish actuation. Repair and overhaul replace sealing and actuation parts, restore the closure mechanism, and verify leak-tightness, response timing, and pressure capability.

Aircraft Application

Part number 778686-4 (High Pressure Shutoff Valve) is installed on the Bombardier Dash 8. QTC supports operators and MROs servicing this platform with certified repair and overhaul.

Our Repair Capability

QTC repairs and overhauls 778686-4 to the original manufacturer's specifications under our FAA and EASA Part 145 approvals. Our team — including former OEM pneumatic & air management 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.

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Related Parts

Other high pressure shutoff valve part numbers we repair — view all High Pressure Shutoff Valve parts →

Frequently Asked Questions