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Since the largest fluid system in any aircraft is typically its fuel system, then it stands to reason that the design of fuel pumps needs to be continually evaluated and optimized. Aircraft manufacturers need to explore all possible advances in manufacturing, materials, and health monitoring to help aircraft operators capitalize on greater efficiency, weight savings, longer life, and reduced costs. As a leading manufacturer of aircraft fuel boost and transfer pumps, Parker Aerospace has its pulse on probabilistic design and conceptual methods that may offer systematic gains to stakeholders in the commercial and military aviation markets.
Additive manufacturing already has a role in the aerospace industry as a rapid prototyping technology, enabling manufacturers to save time and cost during product development. Three-dimensional printed components allow Parker Aerospace’s Fluid Systems Division to build pumps with fewer parts and get them to the test stand quicker. Lessons learned in the prototyping phase can affect product design, manufacturing, assembly, and aftermarket repair. 
Application of composite materials
Prognostics health monitoring (PHM)
Parker’s fuel boost and transfer pumps have been selected by Airbus for use in its A350 aircraft and by COMAC for its C919 aircraft. In addition, the Fluid Systems Division is working to provide significant bill of materials, including fuel system, fuel boost and transfer pumps on several large aircraft programs slotted for entry into service over the next decade.The History and Pedigree of Parker Aerospace Fluid Systems Division Fuel Pumps
Customizable Aircraft Fuel Pumps Reduce Cost and Boost Reliability
New Optical-Based System Will Transform Aircraft Fuel Measurement
Parker Aerospace’s Fluid System Division has a long history of supplying fuel pumps to both the civilian and military aviation markets. Detailed analysis and testing, combined with extensive hours of field operational experience, ensure our off-the-shelf pumps provide a proven, low-risk, and cost-effective solution for aircraft fuel system design.
Whether a fuel system requires a boost or transfer pump, each design within Parker’s product-line family has unique features and can be fully customized to meet specific operational requirements for fuel type, delivered flow, inlet/discharge pressures, and temperatures (fluid and ambient). Variations in mounting configuration, available electric drive power, and allowable installation weight can be accommodated to provide a fully customized solution if an existing design is not satisfactory for any new or retrofit applications. All pump models are designed to the requirements of MIL-STD-704, MIL-STD-810, ARP-5794, and RTCA DO160.
Parker Aerospace fuel pumps typically perform two functions within the fuel system. A “boost pump” supplies pressurized fuel from the main supply tank directly to the engine. A “transfer pump” moves fuel from one tank to another to maintain the center of gravity of the aircraft and to ensure the primary tanks remain full during flight. Pump selection is based on the requirements for delivered flow and pressure, as well as the available electric power system of the aircraft. To supply the optimal off-the-shelf solution, any specifications associated with a new application should be sent to Parker so the best available option can be selected and presented to the customer.
Parker’s fuel pump product lines
28 VDC brushed fuel pump
Designed for general aviation, business jet, and rotor aircraft, these brushed pumps run on a 28 VDC power system and perform both the boost and transfer functions in the fuel system. The direct-drive motor features carbon brushes that power a wound armature shaft. Hydraulic elements include centrifugal and vane assemblies. Pump mounting arrangements are tank submerged (wall and floor), in-line (outside the fuel tank), and cartridge/canister (wall and floor mounted with the pumping element removable without draining fuel from the tank).
Programs supported:
Designed for civilian and military aircraft, these brushless pumps run on a 28 VDC power system and perform both the boost and transfer functions in the fuel system. The pump is powered by a brushless DC drive system that consists of a permanent magnet motor and an analog electronic controller. Hydraulic elements are centrifugal assemblies. Pump mounting arrangements are tank submerged (floor), and cartridge/canister (floor mounted with pumping element removable without draining fuel from the tank).
Programs supported:
270 VDC brushless fuel pump
Designed for military aircraft, these brushless pumps run on a 270 VDC power system and perform both the boost and transfer functions in the fuel system. The pump is powered by a brushless DC drive system that consists of a permanent magnet motor and a digital electronic controller that runs on configuration-controlled software. Hydraulic elements are centrifugal assemblies. Pump mounting arrangements are tank side-wall (bracket) mounted.
Programs supported:
Designed for regional jets, rotor aircraft, and military aircraft, these pumps run on a 200VAC (L-L), 400 Hz constant frequency power input and perform both the boost and transfer functions in the fuel system. The electric drive is a classical induction motor with a copper-wound stator and squirrel-cage rotor. Hydraulic elements include centrifugal and gear assemblies. Pump mounting arrangements are tank submerged (wall and floor), in-line (outside the fuel tank), and cartridge/canister (wall and floor mounted with the pumping element removable without draining fuel from the tank).
Programs supported:
Variable frequency AC (small frame and large frame) fuel pump
Designed for small and large commercial transport aircraft, regional jet, and military aircraft, these small frame and large frame pumps run on a 200VAC (L-L) and 400 VAC (L-L), variable frequency power input (360 to 800 Hz) and perform both the boost and transfer functions in the fuel system. The electric drive is a classical induction motor with a copper-wound stator and squirrel-cage rotor. Hydraulic elements include centrifugal assemblies. Pump mounting arrangements are tank submerged (floor), and cartridge/canister (wall and floor mounted with pumping element removable without draining fuel from the tank).
Programs supported:
Parker Aerospace is increasing its production capability to supply fuel pumps to every market segment, from general aviation to military and large commercial transport. Our FSD-Elyria, Ohio, facility works with numerous key sub-tier companies to form a solid supply base, coupled with fabrication, assembly, and test facilities to supply every customer with products from small to large order quantities. Parker is committed to keeping pace with our customers’ needs.
For more information about Fuel Systems Division fuel pumps, please visit the Parker Aerospace off-the-shelf product page.
This post was contributed by senior principal engineer Bill Heilman of the Parker Aerospace Fluid Systems Division.
The History and Pedigree of Parker Aerospace Fluid Systems Division Fuel Pumps
New Optical-Based System Will Transform Aircraft Fuel Measurement
F-35 Lightning II Fuel and Inerting System Powered by Parker Aerospace
Maintaining Turbine Clearance Control of Aircraft Gas Turbines
Evolution of Fuel Tank Inerting for the Aerospace Industry
Catalytic Inerting Technology: Next Generation Fuel Tank Inerting Solution
Challenged by the industry to advance the fire protection of hoses used in aircraft engine applications, engineers at the Parker Aerospace Stratoflex Products Division have used standard, low-cost materials to create a high-temperature flexible hose (HTFH) that redefines hose life expectancy. HTFH replaces traditional solutions, including both standard flexible hose and rigid pipe, to provide more durable fire protection, vibration damping, and thermal expansion flexibility to the feeder lines that supply the nozzles spraying fuel into the combustion chamber of jet engines.
Vibration is a growing challenge for today’s engine manufacturers. While new lean-burn engines deliver a more complete combustion of fuel that results in lower NOx and particulate emissions, they can cause more vibration or rumble in the engine. Additionally, lighter and thinner components used to reduce engine weight are more susceptible to vibration.
Traditional technologies used to connect fuel manifolds to nozzles are problematic, even potentially dangerous:
Our high-temperature flexible hose is a win-win for engine manufacturers. With a temperature rating of 800°F for ambient conditions with minimal fuel flow of 0.07 gpm, the kink-resistant innovation has inherent damping capability, reducing vibration sensitivity. Plus, it is easier to install, less sensitive to tolerance stack up, offers equal fire-resistance performance to integral fire sleeve hose, and eliminates the problem of thermal aging of fire protection material.
Constructed with a robust, stainless steel outer braid that is superior to a silicone fire sleeve for abrasion and chafing, HTFH has an insulating layer that acts as a fire sleeve. This insulating layer:
Conclusion
The end result of this advanced engineering is a product that is much less costly to maintain due to ease of replacement and significantly longer service intervals, projected to be minimum of 15 years.
Qualified in -4 and -5 sizes (1/4 inch and 5/16 inch diameters respectively) and adaptable to a wide variety of fitting styles and configurations, HTFH is redefining the market.
For additional information on Parker Aerospace systems and capabilities, please visit our website.
This post was contributed by Tracy Rice, strategic chief engineer – engines for Parker Aerospace Stratoflex Products Division.
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Keeping Aircraft Fleets Healthy Around the Clock and Around the Globe
As global air traffic continues to grow, the need for cleaner, more efficient airplanes is rising right along with it. In an effort to reduce the global impact of pollution attributable to aviation, the International Civil Aviation Organization (ICAO) adopted new CO2 emissions standards in 2017 for commercial aircraft, requiring new aircraft type designs to meet these standards before delivery. These regulatory requirements, coupled with airlines’ desire to reduce fuel expenses and other costs, drive engine makers to seek every possible advantage in producing more efficient aircraft engines.
One way to reduce an aircraft engine’s emissions and improve engine performance is through active clearance control (ACC). This is achieved by managing the clearance between the gas turbine casing and the tips of the rotating blades, referred to as turbine tip clearance. An engine’s turbine clearance control system (TCCS) relies on turbine clearance control valves (TCCVs) to control this tip clearance by managing the thermal expansion of the turbine case that surrounds the turbine stages of the engine.
The Fluid Systems Division of Parker Aerospace developed its line of TCCVs with a goal of exceeding customer requirements for reliability, safety, and performance. The product offers engine manufacturers a proven control mechanism that has not only undergone extensive testing but demonstrated improvements in engine fuel burn, which translate into measurable savings for its engine and airline customers.
Turbine clearance control: helping engines maximize efficiency
Turbine tip clearance between the turbine blades and the turbine case is a key parameter that influences turbine efficiency and the propulsive efficiency. The tip clearance should be kept to a minimum value, considering the turbine blade and the case expansion resulting from temperature excursions during the entire operating envelope of the engine. These temperature excursions are a result of the extremely hot combusted gases that enter the turbine stage of the engine, downstream of the combustion chamber and provide the thrust required to power the engine.
The combusted air temperatures can be in excess of 2,000°F, resulting in the expansion of the turbine blades and the case, thereby increasing the tip clearance and loss of turbine efficiency. The net effect is that more fuel needs to be combusted to compensate for this loss of efficiency, in order to generate the required thrust, resulting in increased fuel burn and increase in specific fuel consumption.
Monitoring of the turbine temperatures controlled by TCCVs
By controlling the thermal expansion and contraction of the engine’s turbine casing over its operating envelope, engine manufacturers can better optimize the turbine tip clearances in the engine. A proven method of controlling this clearance is to either direct cooler air around the turbine case to cool and contract the casing ‒ or ‒ to restrict the cooler air, allowing the casing to expand when required to compensate for the turbine blade expansion. thereby maintaining the tip clearance.
This delicate balance is realized through temperature sensors in the engine that measure turbine air temperatures during the entire flight cycle. This information is relayed in real time to the engine’s full authority digital engine control (FADEC), an autonomous, system that monitors and controls all aspects of an engine’s operation, including its turbine tip clearance control system.
Depending on the flight status, the FADEC sends electrical commands to the engine’s turbine clearance control valves, signaling them to incrementally open or close (modulate the flow through the valve), to control the case thermal expansion. The opening and closing of these valves ultimately controls the amount cooling air taken from the engine’s bypass flow to manage engine casing temperatures, thereby facilitating optimum blade tip clearance control.
Parker’s TCCV consists of a butterfly valve actuated using an integral fuel-actuated actuator. The fuel actuator consists of a Parker electro-hydraulic servo valve (EHSV) integrated as part of the actuator. The EHSV receives an electrical command from the FADEC and directs the fuel flow appropriately for the actuator to either extend or retract the actuator rod. Actuator retraction or extension results in modulating the valve position to either fully open or fully closed or anywhere in between, depending on the stage of flight.
The actuator and the valve position are monitored by a linear variable displacement transducer (LVDT), which is integrated within the actuator rod. The LVDT provides the position feedback to the FADEC, which through its built-in software deduces the position of the valve (hence, the TCCV flow). Therefore, the TCCV valve system forms a closed loop sub-system with the FADEC; it receives a command, executes, and relays back the result of its action back to the FADEC for further instructions.
Parker’s turbine clearance control valves: proven gatekeepers
Turbine clearance control valves operate in a hostile environment, being exposed to aircraft engine surrounding air temperatures that can range from -65° to 350° Fahrenheit. The valves also handle the contaminated air flowing through them, as well as engine-induced vibration, and continue to function throughout the engine life.
To survive and perform in this environment, Parker’s butterfly-type valve incorporates several design features to enhance valve life, reliability, and performance. Features such as specially designed dynamic seals have been validated for long-term performance under extreme conditions, enabling superior sealing capability, low friction, and high wear resistance.
These seal designs are critical in ensuring that air flowing through the valve does not leak externally. This type of leakage is wasteful; not only does it rob the thrust-producing bypass air, it also results in less-than-optimum functionality of TCCV sub-system. Together the valve and actuator designs have a proven track record of meeting strict fire requirements during flight certification. The mechanical linkages between the actuator and the butterfly valve shaft are designed to withstand the vibration and endurance cycles required to ensure accurate position feedback and control of the TCCV system.
Parker’s Jet-Pipe® electrohydraulic servo valve (EHSV), designed and manufactured by the Parker Aerospace Control Systems Division. The EHSV is a proven, robust two-stage design that is contamination-resistant, providing the accuracy needed to precisely move the actuator to its commanded position, while providing the durability needed for long, trouble-free service life.
Parker Aerospace’s Fluid Systems Division in Irvine, California, has been providing TCCVs to engine manufacturers for nearly 40 years, continually improving the design and performance of its valves, making them extremely accurate and durable. Our longstanding engine customers include Rolls-Royce, GE Aviation, and Pratt & Whitney, among others.
Tested and retested, again and again
Parker’s Fluid Systems Division offers its customer the benefit of extensive in-house testing capabilities for its TCCVs as well as its full line of products and systems. Parker TCCVs are designed and tested to meet and exceed vibration and endurance life requirements.
Complete endurance testing of the valves to multiple life cycles, which includes applying a full flight profile to simulate flight conditions and mimic valve performance in flight, helps ensure a TCCV design that has achieved maturity at entry into service. Our endurance test routines also include the introduction of contaminants to further prove the valves’ integrity. Additionally, we provide complete control system simulation models of the TCCV control system, utilizing either SIMULINK or Amesym for our engine customers, who in turn use this model within their larger engine control system model.
Engineered for the long haul, easily maintained
By working with our engine customers and aircraft operators, Parker FSD engineers have turned lessons learned into bankable savings for our end-use customers. The valves are designed for maintainability with the goal of lower removal and installation times on wing while achieving optimum repair and overhaul times. Put very simply, Parker valves offer lower total-lifecycle cost proposition for our customers.
Conclusion
The extensively tested and proven technology of Parker’s turbine clearance control valves allows aircraft engine manufacturers to achieve their desired engine performance, including extended service life while reducing fuel consumption (lower specific fuel consumption) and fuel emissions. By helping airlines meet more stringent international standards for CO2 emissions, Parker and its engine manufacturing partners become part of a global commitment to ensure an environmentally responsible future for aviation.
For additional information on Parker Aerospace systems and capabilities, please visit our website.
This post was contributed by Sanjay Bhat, new business development manager for Parker Aerospace’s Fluid Systems Division.
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Evolution of Fuel Tank Inerting for the Aerospace Industry
Parker Aerospace’s Fluid Systems Division has developed critical fuel-vent and line static dissipating tubes in collaboration with OEM customers to safeguard today’s modern composite aircraft from the risk of fuel-tank ignition and serious safety incidents.
Why composites for aircraft
Once used only for light structural pieces or cabin components, carbon composites are now being utilized for wing and fuselage skins, engine components, and landing gear. Lightweight and strong, composites reduce weight and increase fuel efficiency while being easy to handle, design, shape, and repair. They also offer improved reliability and durability while reducing the number of heavy fasteners and joints in an aircraft, which are potential failure points.1
Aircraft manufacturers have been attracted by the advantages of composites. New aircraft using composite wings provide lower fuel use per passenger than comparable aircraft.2 Carbon composites have been portrayed as the perfect aircraft material – except for in the way that they handle lightning strikes.
The impact of lightning on aircraft
According to an article in Scientific American, “What happens when lightning strikes an airplane,” each U.S. commercial aircraft is struck by lightning more than once every year, usually attaching first to an extremity like nose or wing tip3.
Aircraft with an aluminum fuselage and wings can readily conduct the charge from a lightning strike, allowing the current to move along the skin and pass back into the atmosphere. However, composites are significantly less conductive than aluminum.
On composite structures, the current from a lightning strike does not have a highly conductive pathway that allows the electricity to transfer back into the atmosphere. Without dissipation, the lightning currents could ignite the fuel in the fuel tanks, fuel lines, and fuel vents. That’s why our fuel vent and line static isolating tubes are so valuable.
Our fuel vent and line static isolating tubes
Composite wings need isolating and dissipating tubes to slowly dispel the static charge from a lightning strike, thereby preventing arcing in the system. Installed in-line with the fuel lines and fuel vents, the tubes resist electrical energy and eliminate its transfer across the tube. This protects the fuel lines and the rest of the fuel system from possible combustion.
Proven in the air
Our fuel and vent line static isolating tubes are tested and proven. The components are currently installed on all HondaJet business aircraft as well as Northrop Grumman Global Hawk unmanned aerial vehicles. Available in multiple diameters, including 1/2-, 3/4-, 1.0-, 1.25-, 1.5-, 1.75-, 2.0-, 2.5-, 3.0-, 3.5-, and 4.0-inch inner diameter, the tubes are available with ferrules on each end and tubes with a flange mid span to meet most installation requirements.
Conclusion
The growing use of composites in aircraft manufacturing will increase the need for technologies that maximize the advantages of composites while minimizing their limitations. Our fuel-vent and line static isolating tubes will continue to play a critical role in keeping more-composite aircraft safe from ever-present lightning strikes.
For additional information on Parker Aerospace systems and capabilities, please visit our website.
This post was contributed by Glen Kukla, engineering team leader, Parker Aerospace, Fluid Systems Division
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