Aircraft Fuel Efficiency – What’s In The Future?

August 22, 2011 in Fuel Tank Inspection, Jet Fuel Systems by admin | No comments

Overview

The consistent rise in fuel costs has spurred investment in new technologies that will increase aircraft fuel efficiency. These new technologies range from alternative fuels to new designs in various aircraft components.

Alternative Fuels

The rising fuel costs, energy supply, security and aviation emissions have created a need for a fresh look at alternative fuels. Some new fuel types being reviewed include:

Synthetic fuels

Known as synfuel, this is any liquid fuel created from coal, natural gas or biomass. It can also refer to fuels derived from oil shale, tar sand, waste plastics or the fermentation of biomatter. Several large companies are developing coal- or gas-to-liquids processes including Sasol, Shell, Exxon, Statoil, Rentech and Syntroleum.

Biofuels

Biofuel is made from converted agricultural crops like soy. Over the last two years, there has been an increase in interest in biofuels in the aviation industry. For example, British Airways recently announced the construction of a waste biomass gasification plant to produce renewable aviation biofuels. IATA announced that five airlines successfully tested biofuels and that certification is expected by 2011.  To put this in perspective, in the US alone, aviation biofuel is estimated to be a $100 billion plus opportunity.

Ethanol fuel

While mostly used to power cars, it can be used to power other vehicles such as farm tractors. It is hoped that it can be used for airplanes as well. It is typically combined with gasoline in any concentration up to pure ethanol.

New Technologies

Significant enhancements to aircraft have contributed to fuel efficiency. These include airframe design, engine technology and rising load factors. While finding alternative sources to existing aircraft fuel are important, the continual improvement of aircraft fuel efficiency also calls for enhancements to aircraft design and technology.

Revisiting Technology

In 1983, General Electric engineers experimented with an “unducted fan” engine. By eliminating the external casing, airflow through the blades was increased, giving more power for the same amount of fuel. Unfortunately, the engine was quite loud and the project shelved once fuel prices dropped.

Recently, GE began wind-tunnel testing a smaller, scaled set of the blades. The engineers are redesigning the original blades to evenly distribute the air coming off the tips when they spin at supersonic speeds, which should reduce the noise.  The engine is designed to save fuel by tilting the blades to control speed, allowing the turbine to run at a constant, more efficient rate. The design is estimated to be ready for midsize jets around the year 2020.

Diesel Engines

Recently Diamond Aircraft, an Austrian airplane designer, received certification from the FAA for its new DA42, powered by two turbocharged AE300 motors. The AE300 can produce 100 percent power to 11,000 feet thanks to the turbochargers, powering the twin engine airplane to a 152 knot cruise speed while consuming just over 5 gallons of fuel per hour in each engine.

Diesel engine conversion was a US STCed for many Cessna 182s in 2006. While modestly expensive, an aircraft owner will receive a 30 percent or more fuel savings making the overhaul worth investigating.

The Future

Many interesting alternative fuels and technology enhancements are under investigation, making the future of aircraft fuel efficiency much brighter than we have seen before. Some of the alternative fuels are available in the very near future; other enhancements still require significant development. Either way, an owner and/or pilot has options to increase aircraft fuel efficiency and save money.

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Aircraft Fuel Efficiency-Where Are We Now?

August 8, 2011 in Aircraft Fuel Leaks, Fuel Tank Inspection by admin | No comments

Overview

The last two decades have not yielded much in the way of improved aircraft fuel efficiency. In fact, a recent study performed by the International Council on Clean Transportation stated commercial jet aircraft have not made continuous improvements over the last 20 years, citing the stability of jet fuel costs as one of the factors. However, with the recent increase in fuel prices, the industry has a need to improve aircraft fuel efficiency and is looking for methods to assist. Methods currently in use are lighter weight components and aircraft modifications, including the addition of winglets. Because of this more recent trend, we will investigate what is presently available to help improve aircraft fuel efficiency.

Ultem Polyetherimide

A recent improvement is the development of lower weight materials for aircraft. For example, SABIC Innovative Plastics created Ultem polyetherimide in the cellular form. This is 10 to 20 times lighter than traditional plastic components making it an ideal core material for aircraft structures such as luggage compartments, galleys and lower wall panels. Based on the Ultem polyetherimide (PEI) resin, the material has a density of 10 to 30 times less than traditional materials. Plus, it is compatible with metals and thermoset laminate materials thereby increasing its uses to operations that could eliminate adhesives.

In addition to being ideal for many composite manufacturing processes, such as machining, vacuum bagging and compression molding, the new Ultem foam provides good acoustic, dielectric and thermal properties. Additionally, it has low moisture absorption which could eliminate edge filling in some interior areas and reduce weight, which ultimately increases aircraft fuel efficiency.

Winglets

Many jet aircraft are now equipped with winglets, a vertical or tilted structure at the end of an aircraft wing. These devices are in place to minimize the spiral vortices that form at the end of a wing, creating drag on the aircraft, thereby improving fuel efficiency.

Boeing and Airbus are working on new winglets that change shape mid-flight resulting in a quieter and more fuel-efficient trip. These organizations filed patents in 2009 for their technologies.

The Airbus “Morphlet” engineers state that current technology saves between three to five percent of fuel used during normal flight. Airbus engineers believe by allowing the winglets to vary during flight, the higher five percent fuel savings will occur throughout the entire flight. On the other hand, Boeing intends to use SMA panels to move the winglets based on electric current or heat.

Whether these new types of winglets will come to fruition remains to be seen. However, existing winglets offer a reasonable increase in aircraft fuel efficiency, making them a viable solution.

Other Aircraft Modifications

There are several drag-reducing aerodynamic enhancements that can be made to your aircraft to increase speed and decrease flight time, including:

  • Gap seals for flaps
  • Ailerons
  • Wheelpants
  • Gear fairings
  • Exhausts
  • Landing light covers

These enhancements can work together to increase knots, decreasing total flight time. The basic math is that each one percent increase in cruise speed will save you one percent in time. Less time in the air means less fuel burned, saving you money over time.

Another modification to be considered is engine or propeller improvements to produce more power. This increased power enables you to save fuel by using less throttle to maintain airspeed. These modifications should be made under either a supplemental type certificate (STC) or field approval modification. You can find a list of all STCs through the FAA Website. Simply search for the make and manufacturer of the aircraft, and then find your particular aircraft. More popular models may have over 200 STCs available, so plan on the research taking a bit of time.

What’s Next

In spite of the modest changes to aircraft over the last 20 years, fuel efficiency can be improved through existing technology and common-sense modifications. Fortunately, engineers are actively researching new ways to improve fuel efficiency and the overall design of aircraft. In our next article, we will investigate some of the new ideas being considered that will improve aircraft fuel efficiency.

As always, our technicians at Global Aircraft Service, Inc. are available to offer expert advice on your fuel tank inspection and repair needs.

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Pre-Purchase Inspection with a Fuel Leak Check

July 25, 2011 in Fuel Tank Inspection, Jet Fuel Systems by admin | No comments

Overview

The days of purchasing an aircraft without a pre-purchase inspection are gone. Today’s aircraft should be thoroughly inspected to ensure they meet all appropriate safety and mechanical requirements, particularly in light of the fact that many aircraft on the market have over 10,000 service hours. Coupled with the increased value of light aircraft, any mechanical issue could cost significant dollars and put your safety at risk.

First Steps

As the buyer, you are responsible for the pre-purchase inspection. Once you have decided upon the aircraft you wish to purchase, you must decide on the mechanic who will perform the pre-purchase inspection. This is an important decision. You want a mechanic who has performed pre-purchase inspections before, and has the right tools for the job. Most importantly, you do not want the mechanic who has maintained the aircraft to perform the inspection. A fresh set of eyes is crucial for a solid pre-purchase inspection.

The cost of any inspection is directly related to the complexity of the aircraft. Typically, a mechanic can perform a pre-purchase inspection on most fixed-gear, single engine aircraft in four man-hours or less.

Make sure you inspect every log book from the initial purchase of the aircraft. Technological advances and better maintenance procedures mean that aircraft are in the air longer – often over 15 years. They have had various repairs, upkeep and general maintenance performed to keep them in good shape. This information is critical in determining if any damage has been done to the aircraft as well as in determining market value.

Important Tests

It is recommended you invest in deeper testing to ensure the safety and soundness of the aircraft. For example, in addition to a compression check of each cylinder, choose to have an engine boroscope for each cylinder. Consider having the engine oil and airframe hydraulic systems analyzed. Other tests to consider include:

  • Symmetry Check
  • Fuel Leak Check
  • Heavy Landing Check
  • Lightning Strike Check

Other checks will need to be considered based upon the aircraft’s composition. Additionally, verification of the serial number, Service Bulletins and Letters, Supplemental Type Certificate changes and Major Component Total Time in Service records, and in particular Airworthiness Directives, are very important to verify.

Airworthiness Directives, known as AD notes, are mandatory changes, inspection, or repair instructions issued by the FAA. Your mechanic should be able to provide a list of applicable AD notes and should cross-check his list against the logs of the aircraft. You want to know if the aircraft is in compliance with every AD or you risk significant expense.

Get the Facts

As with any major purchase, the more information you gather, the better your decision-making process will be. The pre-purchase inspection, log review and deep testing will let you know if the aircraft is in good condition and safe to fly. If you do find issues, feel free to negotiate the repair with the seller. Much like purchasing a home, it is acceptable to request either to repair the problems or consider reducing the price so you can make the repairs using your mechanic. Investing in pre-purchase inspections and testing will ensure your ownership of the aircraft is enjoyable and safe.

At Global Aircraft Service, our skilled technicians are available to assist with your fuel tank pre-purchase inspection repairs.

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Don’t Be Grounded Due to Aircraft Fuel Leaks!

July 10, 2011 in Aircraft Fuel Leaks by admin | No comments

Overview

Repair of an aircraft fuel system takes considerable time. However, as one of the three primary causes of grounding, fuel leaks are serious issues that must be addressed quickly. Not only can they cost money in precious fuel, but they can also create more serious problems such as fuel starvation to your aircraft’s engines. Choosing to engage in a thorough, systematic approach to aircraft fuel leaks repair will save you time and money.

There can be multiple causes of fuel leaks including:

  • Stress
  • Structural defects
  • Degrading sealants.
  • Increase cycle times

In order to inspect for leaks, the mechanic must first know your aircraft fuel systems. Repair before the basic information is gathered will be a waste of time and money.

Aircraft Fuel Tanks Repair

Devising a sound fuel maintenance process is the first step to ensuring appropriate fuel leaks detection. There are several criteria that should be considered when detecting and repairing aircraft fuel leaks, including:

  • Properly identifying the cause of the leak
  • Identifying the type of fuel system
  • Careful tank inspection, including removal of panels
  • Performing the correct repair based on the fuel tank system

The first step, identifying the cause of the leak, is performed by an aircraft mechanic who recognizes the appropriate steps. These steps include noting where the leak appears, does it only occur when the tank is full, and does the leak stop when the tank is half full. Because a leak can travel a considerable distance before a drop actually appears, the mechanic will need to perform an aircraft fuel systems inspection.

Identifying the type of fuel system through careful review of the maintenance manual gives the mechanic information required to gain access to the fuel tank. There are three types of fuel tanks:

  • Integral (known as “wet wing”) in which the tank is part of the aircraft’s wing
  • Fuel cell, which is a rubber bladder inside the wing
  • Built-up metal or fiberglass tanks, which reside inside the wing

Each of the three types has potential points for leaks. The mechanic must know which fuel tank system he is dealing with and how to approach the inspection and repair process.

Careful inspection of the aircraft’s fuel tanks is the next step. Removing the appropriate panels and thoroughly inspecting areas of the fuel tank can uncover the actual cause of the leak. This inspection requires both visual inspection and odor detection. While 100 low-lead aviation fuel is blue and will leave a blue stain when dry, jet fuel is colorless. However, it leaves a strong odor and is slow to dry making it detectable by a trained mechanic. The mechanic will need to also make sure all connections and clamps are tight.

If the source of the leak is determined to be the fuel tank, the next step is to remove it to perform appropriate repairs. An integral tank cannot be removed as it is part of the aircraft’s wing. Therefore, repairs must be made with it intact. The other fuel tank systems can be removed using the instructions in the aircraft’s maintenance manual.

Once the aircraft’s fuel tank repair is completed, the fuel system must be reinstalled according to the maintenance manual. Careful attention to detail when attaching panels is required. Also, the mechanic must look for new leaks during the installation process. It can take up to 24 hours for small leaks to be visible. Therefore, the fairings should be left off until the mechanic can determine there are no aircraft fuel leaks.

Repair of aircraft fuel systems cannot be rushed. This process takes time and careful investigation to ensure the actual cause of the leak is detected. Specialized training is often required for the mechanic to correctly repair fuel tank leaks. Once all the repairs are completed, more time is required for the mechanic to ensure no new leaks have occurred during the installation process. Furthermore, aircraft fuel tank repair often requires new sealant. To ensure no future leaks, it is important to follow the manufacturer’s curing time recommendations which can add significantly to the time needed for repair.

Fuel leaks can cost considerable time and money. By taking the appropriate amount of time to thoroughly investigate and make aircraft fuel systems repairs, you will ensure longer flight times going forward.

At Global Aircraft Service, our skilled technicians are available to dispatch to assist with your fuel tank repairs.

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Microbial Growth in Aircraft Fuel Storage

June 17, 2011 in Jet Fuel Systems by admin | 1 comment

Overview

Every day millions of gallons of aircraft fuel are used to facilitate flights of personal and commercial aircraft.  This aircraft fuel must be stored and transported based upon the numbers and types of flights occurring. While airlines, airports and fuel service companies do their best to ensure the fuel stays clean, the reality is that many contaminants can infect the fuel either during storage or transport. Water, air and soil are the primary culprits for contamination.

Any time fuel and water come into contact, certain bacteria and fungi can grow and propagate quickly. The most destructive microbe in aircraft fuel is the fungus Hormocconis resinae. It produces far more biomass that single-cell yeasts and molds and is the most common cause of microbial corrosion in aircraft fuel tanks.

Microbial growth produces a sludge-like substance that can cause corrosion on steel and aluminum surfaces and attack rubber fuel system components. Additionally, microbial growth can also contaminate filters and system instrumentation.

While modern techniques ensure that aircraft fuel is almost totally free of undissolved water upon entering the aircraft, temperature variations on the ground and in flight can result in condensation that build up to form a water bottom. Additionally, long-term storage facilities are at risk due to potential aircraft fuel degradation or the risk of microbial growth in untreated diesel and jet fuel.

Left untreated, microbial growth can cause major problems, including:

  • Contaminated fuel
  • Additive degradation
  • Structural damage
  • Filter plugging
  • Slime growth

Fortunately, there are treatments and preventative measures that can be taken to ensure clean fuel is readily available.

Treatment and Prevention

An important aspect of maintaining high quality in aircraft fuel is the design of the fueling system. This system must minimize the potential for fuel contamination. The current practice is to coat the internal areas of the piping, storage tanks and major equipment using high solids epoxy paint effective for hydrocarbon immersion service. The slick surface will minimize corrosion and sediment build-up on the majority of equipment surfaces.

In the case of long-term storage facilities, treating aircraft fuel with the element boron will often get rid of the microbial growth. However, the boron levels must be monitored to avoid over-treating the fuel. This is easily accomplished through routine sampling and testing, and is particularly important to perform regularly on storage tanks and aircraft that have been grounded for extended periods.

There are additives available that will also get rid of microbial growth. These additives will quickly eliminate all kinds of microbial contamination, often within hours of use. Additionally, they allow the aircraft fuel to remain protected over long periods of time while resisting additional contamination of other sources.

Fuel tanks and sumps should be drained of water regularly and checked for slime growth. This will reduce the likelihood of microbial contamination. It is important to remember to cap fuel lines during maintenance operations to prevent particulates from entering the system. Otherwise, the maintenance process designed to prevent issues can actually cause them.

Field kits can assist in both detecting the presence and contamination source of microbial growth. Additionally, there are field kits available to monitor for early warning signs that provide an opportunity to proactively treat for microbial growth.

While aircraft fuel contaminants can prove difficult to control, employing a solid fuel quality monitoring system through a series of tests will ensure that aircraft fuel stays clean. Whether in the aircraft or stored in a long-term facility, it is important to understand the potential of microbial growth, taking appropriate measures to search for it, and then removing any sludge, thereby keeping the fuel microbial free.

Keeping your fuel storage clean with scheduled inspection and maintenance can prevent hazardous situation and grounding of aircraft for longer periods of time, disrupting your operations.

Global Aircraft Service, Inc.

Jet Fuel System Specialists

www.globalaircraftservice.com

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Aircraft Fuel Tank Technician Training

May 23, 2011 in Jet Fuel Systems by admin | No comments

Training

Before a fuel tank maintenance technician can safely enter an aircraft fuel tank, several critical steps included below must be performed:

  • Electrically ground and defuel the aircraft
  • Gather and stand by with properly functioning fire protection equipment
  • Deactivate associated aircraft systems as required
  • Ensure proper ventilation, by applying the proven recommended ventilation techniques
  • Frequently monitoring the air quality within the aircraft fuel tanks

 

Portable gas detectors are used to monitor the oxygen and flammable vapor concentrations within the fuel tanks. Oxygen concentrations should be between 19.5 and 23.5 percent. Levels below 19.5 percent are considered oxygen deficient, while levels above 23.5 percent will significantly increase the risk of fire and/or explosion.  Monitoring these numbers is critical to the safety of the maintenance crew.

Proper training of the maintenance crew is an important component to conducting proper aircraft fuel tank repairs without an incident. These technicians must maintain constant and accurate voice communication and continuously monitor the aircraft fuel tanks and their surroundings’. All technicians must understand the many critical components within the aircraft fuel tanks, to prevent injury to personnel and costly damage to the aircraft.

 

Emergency Response Plan

The unfortunate reality of aircraft fuel systems maintenance is that potentially severe issues can occur. The interior of a fuel tank can be a particularly hazardous environment. Therefore, all aircraft service and maintenance procedures should also include an emergency response plan.

Appropriate training is critical to ensuring the safety of flight. Aircraft fuel systems maintenance is an intricate procedure and requires significant monitoring to ensure the safety of all involved. Proper training and effective processes will support a healthy work environment for fuel tank repair technicians by recognizing hazards and having proper protocols in place to respond to any issues that may arise.

 

Global Aircraft Service, Inc.

Jet Fuel System Specialists

www.globalaircraftservice.com

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Aircraft Fuel Tank Safety & Maintenance

May 12, 2011 in Jet Fuel Systems by admin | No comments

Overview

Aircraft service and maintenance are important functions to ensure safety of flight. After all, you do not want to have a maintenance issue while you are in flight. Every precaution must be taken while the aircraft is on the ground so that you arrive at your destination without incident.

Proper inspection should include a thorough investigation of the aircraft. In particular, the interior of an aircraft fuel tank requires intense scrutiny and attention to detail. The fuel tanks must be checked for multiple discrepancies to include:

  • Fuel leakage
  • Fuel quantity probe replacement
  • Fuel boost pump obstructions
  • Faulty wiring
  • F.O.D.
  • Structural damage to wings (cracks and corrosion)
  • Sealant deterioration

Aircraft Fuel Tank Inspections

To properly perform aircraft fuel tank inspections and maintenance, technicians must physically crawl inside of the fuel tank if accessible. Most aircraft fuel tanks are not large enough for an average sized man to maneuver within easily. For example, the largest fuel tank of a DC-9 measures approximately 2-1/2 feet high, 4-1/2 feet wide and 4-1/2 feet long and are usually smaller on many corporate aircraft.

Due to the hazards of working in such confined spaces, OSHA regulations are in place to protect technicians that are required to perform aircraft fuel tank repair as part of their daily duties.

Additionally, maintenance technicians face multiple dangers while performing aircraft fuel systems inspections and repairs.  Furthermore, jet fuel and other chemicals used internally within the fuel tanks may also contain toxins or irritants that can have adverse affects to the central nervous system.

To protect technicians from these types of hazards, specialized training and procedures are in place.

You can find more information on this topic on our Jet Fuel System Specialists Website.

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