971D (Replaced by 971D1) – SAF-AIR Push-Type Fuel Drain Valve for Textron Aircraft
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The 971D is the original part number for the high-quality, push-type fuel drain valve manufactured by SAF-AIR Products and specified for use on numerous Textron Aviation (Cessna) aircraft. Note to operators and technicians: This part number has been superseded to the current, improved SAF-AIR part number 971D1. This valve serves a flight-critical function, allowing pilots and mechanics to sump fuel tanks, gascolators, and low points in the fuel system to check for water and sediment contamination before flight.
The valve is engineered for maximum reliability, featuring a simple, spring-loaded poppet design that ensures a positive seal when closed. Fuel pressure inside the tank further aids in sealing the valve, making it tighter as fuel head pressure increases. A leaking fuel drain valve is a significant safety hazard, and using the latest revision of this certified component is essential for maintaining the integrity of the aircraft's fuel system.
Key Features
Specified for use on Textron/Cessna Aircraft: The industry-standard valve trusted by the OEM for its reliability and performance.
Simple and Reliable Push-to-Drain Operation: Allows for quick and clean fuel sampling with any standard fuel sampler cup or tool.
Spring-Loaded Poppet for a Positive Seal: The poppet is spring-actuated to snap shut decisively, and is further sealed by the fuel's own static pressure, providing a dual-sealing mechanism.
Fuel-Resistant Elastomeric Seals: The internal poppet seal is made from a durable Nitrile (Buna-N) compound, providing excellent long-term resistance to swelling and degradation from aviation gasoline (100LL).
Corrosion-Resistant Body: The valve body is machined from a corrosion-resistant metal, typically brass or anodized aluminum, for durability in the harsh airframe environment.
Technical Specifications
Original Part Number: 971D
Superseded By / Current Part Number: 971D1
Component Type: Fuel Sump Drain Valve
OEM Manufacturer: SAF-AIR Products (Specified by Textron Aviation).
Body Material: Brass or Anodized Aluminum.
Seal Material: Nitrile (Buna-N) for Avgas applications.
Thread Size: 1/4-18 NPT (National Pipe Taper).
Aircraft Compatibility
The 971D and its superseding part number 971D1 are the standard OEM-fitment valves on a vast range of Textron Aviation (Cessna) aircraft, including but not limited to:
Cessna 150, 152
Cessna 172 Skyhawk
Cessna 177 Cardinal
Cessna 180, 182 Skylane
Cessna 206, 207, 210
Cessna 310
Crucial Note: The correct part number for a specific aircraft model, serial number, and location must be verified using the latest revision of the aircraft's Illustrated Parts Catalog (IPC).
Applications
Fuel Tank Sump Drains: Allows for the draining of the lowest point in the fuel tank.
Fuel Selector / Reservoir Drains: For sumping the fuel selector manifold.
Gascolator (Fuel Strainer) Drains: Allows the gascolator bowl to be drained and cleaned.
Why Choose 971D1?
While your maintenance documents may reference the legacy 971D part number, ordering the current 971D1 ensures you receive the latest production revision from SAF-AIR. The new version may incorporate improved seal materials or other minor enhancements for even greater reliability and service life. A leaking fuel drain valve is a severe fire hazard and can lead to fuel starvation. Using the current, factory-certified part is the best way to ensure a leak-free, airworthy fuel system.
The design of the 971D-series poppet-style drain valve incorporates a dual-sealing philosophy for maximum reliability. The first sealing mechanism is the mechanical force from the internal spring, which provides a constant closing pressure on the elastomeric poppet seal against its machined metal seat. This ensures a positive seal even when the fuel tank is empty. The second, more powerful sealing mechanism is pressure-assisted sealing. The poppet head is designed so that the static pressure of the fuel in the tank exerts a force over its entire surface area. This hydraulic pressure acts in the same direction as the spring, significantly increasing the net sealing force. This means that as the fuel level (and thus the head pressure) increases, the seal becomes progressively tighter. This elegant, fail-safe design ensures a leak-free seal under all normal operating conditions, yet allows for easy actuation with minimal force from a standard fuel sampler.
Note: This is a flight-critical fuel system component. It should be inspected during every pre-flight for any signs of staining or active leakage. A dripping or leaking drain valve renders the aircraft unairworthy and MUST be replaced immediately. During installation, an appropriate, fuel-resistant thread sealant must be used on the NPT threads to ensure a leak-free installation into the tank or fitting. Installation must be performed by a certified A&P mechanic in accordance with the aircraft maintenance manual.
Documentation
The definitive part number applicability for a specific aircraft is detailed in the Illustrated Parts Catalog (IPC). Installation procedures should reference the aircraft's maintenance manual and standard practices such as AC 43.13-1B.