Teledyne Continuous Flow Fuel Injection

Repair Stations Threatened Part 145 recommendations may shut you By Stephen P. Prentice March 2000 Stephen P. Prentice is an attorney whose practice involves FAA-NTSB issues. He has an Airframe and Powerplant certificate and is an...


  • Idle Mixture

    Now, since fuel system adjustments can only be made with the engine off, make only small incremental changes between measurements. If large adjustments are made arbitrarily, system balance may be lost and this may require you have the factory recalibrate the components on a fuel bench.

    If the fuel pump pressure at idle rpm was not specifications as per the engine operational test form, then the relief valve will need to be adjusted.

    Locate the relief valve adjustment on the rear of the fuel pump. Loosen and hold the lock nut and turn the valve clockwise to increase pump pressure, or counterclockwise to decrease pump pressure.

    Once you've completed the adjustment, start the engine and again let the oil temperature and pressure stabilize at 1,500 to 1,800 rpm.

    Now, retard the throttle to the specified idle rpm. Monitoring the tachometer, slowly move the mixture control from full rich to idle cutoff to check the idle fuel/air mixture adjustment. A 25 to 50 rpm rise should occur. If the rpm rise is greater than 50 rpm, the fuel mixture is too rich, if the rpm rise is less than 25 rpm, the fuel mixture is too lean.

    Adjusting the pump pressure and idle mixture requires that the technician achieve a balance between idle 28 Recip Technology pump pressure and idle mixture. So everytime one adjustment is made, the other has to be checked to see how it was affected by the change. Additionally, it can't be emphasized enough that if the engine is not brought up to normal engine temperatures and pressures, and if the engine is not cleared by running to 1,500 to 1,800 rpm between adjust ments, it will not be possible to properly adjust the system.

    To adjust the idle fuel air mixture on engines using the link rod between the throttle and fuel control unit, turn the 3/8-inch lock nut clockwise to enrich the mixture or counterclockwise to lean the mixture.

    The GTSIO-520 idle adjustment requires clockwise rotation to lean the mixture and counterclockwise rotation to enrich the mixture.

    Some engines (IO-240, IO-360, IO-550-G, TSIO-360, TSIO-520-D, DB, UB, BE, and TSIO-550-B, C, and E) use a combination throttle fuel control assembly with incorporated fuel control unit. The idle fuel air mixture adjustment is located in a recess in the fuel control unit cover attached to the side of the throttle body. Clockwise rotation of this adjustment screw will lean the mixture setting, counter-clockwise rotation will enrich the mixture setting.

    Since adjustments are made with the engines turned off, you may need to repeat the adjustments several times before you get it right.

    You have now completed procedures for setting the fuel injection system at idle speed. Next, you need to set the fuel injection system at full power.

    For turbocharged engines, the idle performance adjustments are identical to naturally aspirated engines; however, if you have a turbocharged model, you will need to refer to the turbocharged parameters to adjust full power settings.

    Fullpower settings
    Start the engine again and bring it to normal operating temperatures. Engine fuel flows and pressures vary with engine rpm. With the mixture at full rich and the propeller control to full increase rpm, slowly advance the throttle to full rated power for the engine. Allow the engine to stabilize for at least least 15 to 30 seconds before taking any readings.

    After the engine stabilizes, take the following readings:

    • Fullpower metered and unmetered pressure
    • Fuel flow
    • Manifold pressure
    • RPM

    Retard the throttle to 1,000 rpm and compare the actual readings with the required specifications.

    If pressures and flows are within the specified limits, no further adjustments have to be made and all test equipment can be removed and the aircraft returned to service.

    If the parameters are not within specified values, further adjustments are necessary.

    Turn off and disarm the engine, then locate the adjustable orifice on the fuel pump's vapor separator body. On all fuel pumps, turning the adjustable orifice clockwise will increase unmetered fuel pump pressure; turning it counterclockwise will decrease the unmetered fuel pump pressure. The orifice uses either a 5/32 allen adjustment or a slotted screw adjustment, depending on when the engine was manufactured.

    With this adjustment, you are changing the unmetered fuel pressure by turning the adjustable orifice at the engine driven fuel pump to attain the correct metered fuel pressure and flow.

    Naturally aspirated engines that use an altitude compensating fuel pump allows fuel pump pressure to vary with atmospheric pressure. The aneroid is preset at the factory or at overhaul. It should only be adjusted following a flight evaluation in accordance with TCM Service Information Directive SID-97-3 or the latest revision.

    Perform a complete system operational test and verify that all fuel system parameters are within the specified values for the aircraft and engine.

    Turbocharged engine adjustments

    Although the approach is basically the same for turbocharged engines, the process is different enough that it warrants a careful review of both the aircraft manufacturer's instructions and Service Information Directive 97-3.

    Remember that you may have to disconnect the fuel pressure regulator if installed and reattach the lines, minus the regulator for adjustment.

    Compensating
    One mistake that is often made by technicians is compensating for the pressures specified in the bulletins due to either a removed fuel regulator or the engine not able to make the rated rpm.

    If your turbocharged engine model incorporated a fuel pressure regulator, you adjusted the full-power parameters five percent higher than the published specifications for the engine. Remember to reinstall the fuel pressure regulator removing plugs and caps and reinstalling the line on the regulator.

    The other condition that you may have to compensate for is if the engine is not making full rated power. For instance, if the specifications call for the unmetered pump pressure to be 28.3 to 29.8 psi at 2,625 rpm and the engine will only turn at 2,600 rpm, the unmetered pressure will have to be adjusteAMd down by a factor as listed in TCM's Compensation Table for Static Ground Setup. This table can be found on Page 9 of SID97-3.

    One final note; It's not uncommon to have to repeat these procedures several times prior to achieving desired results. So don't get discouraged if the procedure doesn't produce the desired results the first time. The most experienced technicians may have to repeat the procedure until it's correct.

    Teledyne

    Continuous Flow Fuel Injection Setup

    by Teledyne Continental Motors

    November 1999

    continued...page 3 of 3

    Teledyne Continental Motors Update

    Teledyne Continental Motors has proven to be one of the leaders in innovation with respect to aviation piston engines. With the introduction of fuel injection and turbocharging in the '60s to a liquid cooled engine in 1986, the company is indisputably in the forefront of piston engine development. And, the last couple of years have been no exception.

    ImageGAP engine

    R ecent developments at TCM include a Jet-A fuel burning engine developed as part of the NASA General Aviation Propulsion (GAP) program

    The engine is designed with cast case halves with integral cylinder assemblies.

    The idea is that little or no maintenance will be required until TBO, which is projected to be around 3,000 hours.

    The company says the fact the engine burns JetA fuel will be appealing to operators around the world as Jet-A is readily available worldwide. A prototype is currently in test at the TCM factory.

    FADEC
    The company has also launched into program to upgrade existing technology to electronically controlled engines.

    The FADEC (Full Authority Digital Engine Control) design has come a long way with help from Teledyne's sister company, Aerosance, Inc.

    With the Aerosance FADEC, each engine cylinder is controlled by a dedicated microprocessor and is backed by a second microprocessor. Magnetos are replaced with MPC (Master Power Control) units which control fuel and ignition. Each unit contains the igniter coils (primary and secondary) and fires two cylinders. Fuel injectors are redesigned and control fuel pressure and distribution independently.

    With FAA certification expected late this year, sales of the Aerosance system could begin as early as January of 2000.

    Updated machining and manufacturing
    Additionally, TCM has spent the last several years updating their factory to reduce manufacturing costs and provide ontime support and quick turnaround for their customers.

    President Brian Lewis says the company has invested millions since 1986 and reduced the space required to manufacture and rebuild engines by 75 percent.

    The result is that TCM's manufacturing is more consistent and timely. Computerized tracking process also allow the company to track individual orders through the factory.

    TCM Link
    Although the company has had a computerbased system for communicating and providing information to its customers and TCM Support centers, the company has now converted this system for use on the World Wide Web and has added many new features.

    Access to this page allows TCM-approved service centers to gain access to critical maintenance information, track information on specific engines by serial number, and request quotes for TCM parts from TCM approved distributors.

    Training School

    TCM has now moved its school to the factory in Mobile, AL, with a new emphasis on complete and thorough training of technicians who purchase the one week course. The course includes all the maintenance manuals and applicable documents you'll ever need to adjust and maintain the engine. In addition, the attendee is offered the opportunity to adjust critical components in the fuel injection system on the test bench to gain a true understanding of the affects of the different adjustments.

    The course is well worth the money. For more information or to reserve a space in the class, call Don Fitzgerald, Jr. at (334) 436-8134 or e-mail to

    Window Repair Basics

    A clear view of window maintenance requirements

    July 1999

    Typically, crazing is repairable if addressed early, and if adequate thickness is present to maintain the required minimum thickness of the window.

    Image

    Razor cuts are a common source of damage as a result of cutting masks during painting operations

    Crazing that has progressed to cracks cannot be repaired. Cupery explains, "When you see multiple crazing marks and they are all chained or interconnected, they are then classified as cracks and cannot typically be repaired."

    According to Cupery, crazing was not always a problem in the industry. "Before 1980, crazing was not that bad a problem. Unfortunately, in 1982, the volcano on Mt. El Chicone pumped megatons of sulfur dioxide gas into the atmosphere. This gas quickly circled the earth and was present around the globe. Since then, other volcanic events, such as Mt. Penetubo in the Philippines have added to the problem. This gas mixes readily with moisture in the atmosphere and, at certain altitudes, becomes sulfuric acid. The resulting acid etches the windows and is primarily responsible for most of the crazing we see today. Note that all volcanoes have not contributed to the problem. Some, such as Mt. St. Helen, pumped out lots of ash, but did not produce sulfur."

    Cleaning can result in crazing also, in addition to a host of other damage Ñ essentially, chemicals and heat cause crazing. With this in mind, what you use to clean windows can be responsible for the crazing of your windows.

    Image Adhesive tape used in this Challenger window can cause what is called "corn-flaking."

    First of all, don't use glass cleaners or cleaners that contain ammonia or other harsh chemicals. Use a cleaner that is designed for acrylic. In addition to harsh chemicals, glass cleaners also end up charging the window with static electricity, which means that the window will attract dust, dirt, and other airborne particles. A true plastics cleaner should have an anti-static agent built in. So, use glass cleaners on glass only and use plastic cleaners on acrylic.

    Other items such as adhesives used during masking and painting operations can also result in crazing if the tape residue is not removed after the paint job.

    Methyl Ethyl Ketone (MEK) is particularly harmful to acrylic. In fact, MEK and acrylic windows just don't go together. It will be only a matter of seconds after MEK is applied before it attacks the acrylic and causes crazing. "We have had to repair numerous windows where maintenance personnel used MEK to remove paint overspray or to clean the windows," says Cupery.

    Another source of damage can be from using the wrong sealant. "We have found several cases of this, and typically, if one window exhibits this type of damage, they all will have it," warns Cupery. "In fact, on any given aircraft, damage that is found on one window should lead you to suspect the same types of damage to the remainder of the windows. Don't let anyone talk you into using alternate sealants other than those approved by the manufacturer. Some Ôquick curing' sealants that allow your aircraft to return to service quicker have accelerators in the sealants that can attack the acrylic. Also, RTV 732 has Glacial Acetic Acid in it that will attack the acrylic Ñ so don't use it to make repairs. Additionally, on the other end of the spectrum, there are products that are alkaline in nature (with a Ph level above 7) and can also be caustic and cause crazing."

    Painting operations offer their own set of particular problems related to windows. Cupery continues, "We've done many windows that have razor damage from cutting templates to cover the windows during painting. In the early 80s, paint shops were unaware of the potential damage that could be done to windows. They would cut right into the acrylic, which eventually resulted in many window failures. During one year early in the 1980s, we repaired over 300 Hawker aircraft alone that had razor damage."

    Fortunately, paint shops have become more aware of this problem. The number of windows that require razor damage repair is diminishing over time, as the industry becomes more educated.

    Another problem is related to chemicals and strippers. Most shops know not to let strippers come in contact with the windows, but in an effort to remove paint right up to the edge of the window; they unwittingly allow the stripper to migrate into and under the window flange. The stripper eventually works on the acrylic, weakening the window and causing crazing.

    Image A special prism is required to be used with glycol (as a coupling agent) to view damage to the outer edges of the window

    There are various ways to avoid this, including properly masking the space between the skin and the windows so as not to allow chemicals and strippers to enter, or removing the windows and installing painting blanks. Either way, the cost of taking these extra steps is far less than having to buy a new set of windows.

    Another common cause of crazing is hot patches on windshields. The heat eventually forms fine crazing that begins to distort the pilot's view. Fortunately, up to 80 percent of the crazing that happens to hot patches (heated windshields) can be repaired.

    Shelling/Scaling
    Shelling is the in-plane cracking of the acrylic panel. The damage has a shiny "oyster shell" appearance. Typically this damage will be evident around bolt holes and in the outer radius areas of the window. It may be caused by razor cuts, stress risers on the radius, or over torquing of bolts during installation and is also referred to as scaling. This is a condition that can cause structural failure of the window and must be removed from service.

    "Shelling reflects back at you like the inside of an oyster shell when you shine light directly onto it," Cupery explains. Shelling is difficult, if not impossible to repair and the window usually must be removed from service."

    Debonding
    Debonding is a separation of two or more surfaces that had been bonded together through the use of specific bonding materials, which begin to deteriorate. This is typically evidenced by the formation of moisture and fogging in the windows due to moist air bypassing the desiccant system. Many windows use a desiccant system to remove moisture from the air that is circulated between the windowpanes so as to prevent fogging. This is not a structural problem and is repairable; however, moisture can cause corrosion to occur in some windows, e.g. Hawker D/V windows. Cupery says "Older windows were also more prone to this with some of the Challenger cabin windows having a particular problem of the adhesive tape drying out and flaking into the window. At the time, it was known as a Ôcorn flaking' problem because the flaking cellophane resembled corn flakes. The problem has since been resolved after developing a new seal that doesn't exhibit the same problem. Debonding of double pane windows is evident as the window will fog over and moisture will build inside the window.

    Once debonding begins, it quickly gets worse. What happens is moisture builds in the bottom of the window and between the panes. As the aircraft goes to altitude, this moisture freezes and spreads the panes even further apart Ñ causing further debonding.

    Image Delamination appears as a milky white area that doesn't reflect back.

    Delamination
    Delamination is the separation of the acrylic or glass layer from the polyvinyl sheeting to which it is laminated. Causes are usually stresses from normal airframe torquing or age and UV degradation. This is not considered to be a structural problem and is actually a built-in form of stress relief, yet it may grow to obstruct vision. Repairs, in many are not cost effective, approved, or long lasting. However, we have had some very good success at relaminating some King Air, Soccata, and Falcon windshields. This procedure is successful only if the delamination is clear and there is no moisture ingression. Once moisture is present, which is evidenced by a milky color, the window cannot be relaminated.

    Delamination can be distinguished from shelling because it doesn't reflect back at you when you shine a light on it. Instead, it just appears as clear bubbles, dull flat or white discolored areas. Manufactures have limits for how large an area is allowed. If the area of delamination is within manufacturer's limits, you should monitor the area for growth by marking the edge of the damage with a grease pencil on the inner surface of the window. In any case, if the pilot's vision is affected, the window should be replaced.

    Erosion
    Another thing that can take a toll on windows and cause unexpected stress risers is simple erosion. One example of this is on the Falcon 10 DV (side cockpit) windows. The DV window on this particular aircraft protrudes out into the airstream and airborne dust particles and rain slowly erode the leading edge of the window. We repair these by beveling, within certain manufacturer's limitations, the leading edge so that it is more aerodynamic. This erosion is unacceptable and must be repaired/removed if you notice it or shelling will occur.

    Can your windows be repaired?
    According to Cupery, "Different aircraft windows have different repairability levels. Repairability will depend on how much material exist beyond minimum thickness limitations. Some aircraft manufacturers try to reduce weight and engineer the aircraft with the windows already at minimum thickness. This does not allow for repairability. Others add material for repairability and safety."

    There are also windows that are located in areas that require more attention then others. An example is the Jetstream 31. On this aircraft, there are a lot of problems related to heat and chemicals on the center windshield.

    The interior detail and complexity of the aircraft will often determine whether it is cost effective to take the aircraft window out or not. Often, most of the damage is on the outside, so it is quite cost effective to just leave the window in stalled on the aircraft for repair.

    Cupery stresses that you can't address damage soon enough. Letting damage progress can mean that repair costs go up exponentially. "Often, we take a window back to the shop after quoting a price for minor repair and then have to inform the operator that they've got more damage than expected. This results in more time and costs to remove the damage."

    He continues, "But keep in mind that when we repair a window in the shop, we address much more than just the surface you're looking through. We spend a great deal of time uncovering, inspecting, and repairing the areas of the window that are hidden under the edges of the window openings. This may mean re-radiusing edges and dressing boltholes, and annealing windows to remove stresses when called out by the manufacturer."

    Debonding
    Debonding is a separation of two or more surfaces that had been bonded together through the use of specific bonding materials, which begin to deteriorate. This is typically evidenced by the formation of moisture and fogging in the windows due to moist air bypassing the desiccant system. Many windows use a desiccant system to remove moisture from the air that is circulated between the windowpanes so as to prevent fogging. This is not a structural problem and is repairable; however, moisture can cause corrosion to occur in some windows, e.g. Hawker D/V windows. Cupery says "Older windows were also more prone to this with some of the Challenger cabin windows having a particular problem of the adhesive tape drying out and flaking into the window. At the time, it was known as a Ôcorn flaking' problem because the flaking cellophane resembled corn flakes. The problem has since been resolved after developing a new seal that doesn't exhibit the same problem. Debonding of double pane windows is evident as the window will fog over and moisture will build inside the window.

    Once debonding begins, it quickly gets worse. What happens is moisture builds in the bottom of the window and between the panes. As the aircraft goes to altitude, this moisture freezes and spreads the panes even further apart Ñ causing further debonding.

    Delamination
    Delamination is the separation of the acrylic or glass layer from the polyvinyl sheeting to which it is laminated. Causes are usually stresses from normal airframe torquing or age and UV degradation. This is not considered to be a structural problem and is actually a built-in form of stress relief, yet it may grow to obstruct vision. Repairs, in many are not cost effective, approved, or long lasting. However, we have had some very good success at relaminating some King Air, Soccata, and Falcon windshields. This procedure is successful only if the delamination is clear and there is no moisture ingression. Once moisture is present, which is evidenced by a milky color, the window cannot be relaminated.

    Delamination can be distinguished from shelling because it doesn't reflect back at you when you shine a light on it. Instead, it just appears as clear bubbles, dull flat or white discolored areas. Manufactures have limits for how large an area is allowed. If the area of delamination is within manufacturer's limits, you should monitor the area for growth by marking the edge of the damage with a grease pencil on the inner surface of the window. In any case, if the pilot's vision is affected, the window should be replaced.

    Erosion
    Another thing that can take a toll on windows and cause unexpected stress risers is simple erosion. One example of this is on the Falcon 10 DV (side cockpit) windows. The DV window on this particular aircraft protrudes out into the airstream and airborne dust particles and rain slowly erode the leading edge of the window. We repair these by beveling, within certain manufacturer's limitations, the leading edge so that it is more aerodynamic. This erosion is unacceptable and must be repaired/removed if you notice it or shelling will occur.

    Can your windows be repaired?
    According to Cupery, "Different aircraft windows have different repairability levels. Repairability will depend on how much material exist beyond minimum thickness limitations. Some aircraft manufacturers try to reduce weight and engineer the aircraft with the windows already at minimum thickness. This does not allow for repairability. Others add material for repairability and safety."

    There are also windows that are located in areas that require more attention then others. An example is the Jetstream 31. On this aircraft, there are a lot of problems related to heat and chemicals on the center windshield.

    The interior detail and complexity of the aircraft will often determine whether it is cost effective to take the aircraft window out or not. Often, most of the damage is on the outside, so it is quite cost effective to just leave the window in stalled on the aircraft for repair.

    Cupery stresses that you can't address damage soon enough. Letting damage progress can mean that repair costs go up exponentially. "Often, we take a window back to the shop after quoting a price for minor repair and then have to inform the operator that they've got more damage than expected. This results in more time and costs to remove the damage."

    He continues, "But keep in mind that when we repair a window in the shop, we address much more than just the surface you're looking through. We spend a great deal of time uncovering, inspecting, and repairing the areas of the window that are hidden under the edges of the window openings. This may mean re-radiusing edges and dressing boltholes, and annealing windows to remove stresses when called out by the manufacturer."

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