Maintenance and Certification


Independent Check of Flight Controls
by Steve MacNab, Regional Manager, Aircraft Maintenance and Manufacturing, Prairie and Northern Region, Transport Canada

During recent oversight activities involving aircraft operators and aircraft maintenance organizations (AMO), it was noted that there has been an increase in findings pertaining to independent checks of flight and engine controls. The records reviewed show an inconsistency in performing checks, as well as errors in documenting activity.

All of us should note several things:

The maintenance release cannot be signed until after any required independent check has been completed and the technical record contains the signature of both persons who conducted the independent check. The regulatory chain is clear on this:

  • Canadian Aviation Regulation (CAR) 571.10(1) requires that all requirements specified in section 571.10 of the Airworthiness Manual be met before the maintenance release is signed.
  • Subsection 571.10(4) of the CARs Standard, item "d" of the "Types of Work" table, requires an independent check and completion of the technical record with both signatures.
  • Every technical dispatch system should ensure that flight crews know if maintenance has been done, and if it has, a reasonable outline of what maintenance was done. The journey logbook is the most common source of maintenance information to flight crew. However sophisticated the technical dispatch system, the logbook makes information available to flight crew if they are to satisfy the regulatory requirements.
  • The flight crew has an obligation to make note of the maintenance done, just like they have an obligation to make note of deferred defects. An understanding of what was done, and an awareness of control systems, either directly affected or potentially affected by the access and egress involved in the maintenance, will assist the
    flight crew if there are unexpected observations during subsequent flight segments. This obligation is imposed by good airmanship, if by nothing else.
  • The meaning of "potentially affected" is subtle, but significant. Maintainers generally recognize the need for an independent check when they disturb a control. But if disturbing the control system was not the object of the maintenance task, the fact that it was disturbed may be forgotten and a proper independent check not done. Examples include installation of rigging pins, control locks or clamps, to facilitate work. Wire bundles and flexible lines could be pushed into controls (to provide access for a task), but not returned to a proper configuration when the aircraft is closed up at the end of the job. Tools or material could also be left behind.
  • If control system involvement was either necessary to the maintenance, or possible while gaining access or closing up, flight crew should be especially vigilant in verifying satisfactory control functions.
  • Complacency is the enemy; it is easy to assume that modern aircraft are so reliable that the next flight segments will be uneventful...

Consequently, this is a reminder to aircraft maintenance personnel to continue to emphasize the importance of good technical records, independent checks and maintenance releases; and for pilots to review recent maintenance, deferred defects and minimum equipment list (MEL) items, as a routine part of pre-flight preparation. Someone, some day, will be glad they did.



Spring Review-Best to Avoid Misrigged Flight Controls!

As the spring and summer flying seasons will soon be upon us, annual inspections, float changeovers and commercial aircraft maintenance will be carried out at many airports and seaplane facilities. After maintenance, an aircraft may require a test flight to ensure the system or systems are performing to the required specifications. Hopefully, the pressure of a test flight combined with the rustiness of seasonal pilots does not force them to become test pilots going beyond their competency.

Aircraft maintenance engineers (AME), or the persons performing maintenance on those aircraft to be test flown, must take the time to ensure entries into technical records and logbooks are written in a clear and concise manner. Prior to the test flight, AMEs should make every effort to review the work completed on the subject aircraft with the pilot.

The pilot who will test fly the aircraft must also decide whether they are qualified and competent for the task at hand. If any doubt exists as to the pilot’s qualifications or currency, a different pilot with the proper experience should perform the flight. The pilot must be briefed thoroughly on the extent of the work done on the aircraft.

This is important not only for private pilots and AMEs who perform work outside an approved maintenance organization (AMO), but also for commercial pilots and AMEs who work within an AMO. Several accidents and incidents have taken place over the past few years. These were the result of inadequate pre-flight inspections after maintenance was carried out. At the time the inspections were carried out, it seemed that everything was done to the best of the maintenance and flight personnel’s abilities. However, by looking back on these accidents and seeing where and what errors were made, we are able to incorporate some suggestions into our own pre-flight inspection methods-both with regards to maintenance and flying.

The following occurrences involved misrigged flight controls and are documented on the Transportation Safety Board of Canada (TSB) Web site at http://www.tsb.gc.ca/: a Convair 340/580, TSB report number A97O0077, at Hamilton, Ont.; a Cessna 172, TSB report number A00Q0043, at Maniwaki, Que.; and a Piper Cherokee, TSB report number A01Q0009, at Mascouche, Que. Misrigged flight controls occurrences are not uncommon, and unfortunately, odds are that they will happen again.

What’s wrong with this picture? Would you want to see this during your run-up?
What’s wrong with this picture?
Would you want to see this during your run-up?

Transport Canada issued Airworthiness Notice No. C010, Edition 2, dated 10 October 2001, entitled "Inspection of Control Systems," which explains the regulations applicable to the maintenance of engine and flight controls, and outlines the applicable standards for control systems maintenance. (see Notice at http://www.tc.gc.ca/eng/civilaviation/standards/maintenance-aarpc-ans-c010-557.htm). The document emphasizes the requirement that the person performing the dual inspection be independent of the original work and that the inspection include a verification of the range of operation of the control system.

In Aviation Safety Maintainer 4/1997, the article "Exploring the Problem of Misconnected Controls" used the circumstances of a DHC-2 Beaver occurrence to raise the question of why so many people might miss such an important item as the integrity of flight controls. The article concluded by urging the reader to develop a methodology that uses all available tools to avoid lapses that might result in misrigged controls.

Here are some examples of what AMEs and pilots can do to manage some risks:

  • be uncompromising in ensuring correct logbook entries and signatures;
  • perform thorough visual inspections;
  • follow all of the manufacturer’s recommended procedures to the letter;
  • establish and review emergency procedures before getting in the air.

Flying, just as driving a car, is an activity that involves distinct risks. From the time the aircraft is prepared for a flight, to the time the pilot walks away after the flight- risk control (or risk management) must always be our top priority.



Dangers of Automotive Gasoline Containing Ethanol
by Brian Kenney, Senior Advisor Fuel Quality and Additives, Petro-Canada
This article was originally published in COPA Flight, June 2006. Reprinted with permission.

This is meant as a warning to pilots who are using automotive gasoline, that times are changing. The use of ethanol in gasoline is proliferating and is, or soon will be, mandated in some provinces. Ethanol use in Saskatchewan was mandated to start in the fall of 2006. Therefore, starting sometime around October, gas stations that previously dispensed hydrocarbon-only gasoline may have been forced to supply gasoline containing some ethanol. The conversion was to take about six months. Ontario has similar plans for 2007. Ethanol use in Quebec is also increasing, with the support of the government-which means that at least one major oil company will be selling gasoline with 10% ethanol, starting sometime in 2006. These are new initiatives and therefore add to the existing ethanol use in Canada. A regional oil company and a number of independents in Ontario are already selling gasoline containing ethanol (GCE). Similar trends have started in the west. The federal government has a target to make 35% of the gasoline in Canada contain 10% ethanol by 2010.

One consideration that has not yet been determined by fuel suppliers is whether a non-ethanol gasoline will be available in all areas. This is not guaranteed, and if the worse case scenario evolves, it may be impossible to buy gasoline without ethanol in large areas of the country. This would actually eliminate the practice of many pilots buying gasoline at local service stations and bringing it to the airport to fuel their airplanes. This would also cause a problem for certified aircraft owners using a supplemental type certificate (STC) for unleaded automobile gasoline: most, if not all, of the STCs prohibit the use of ethanol in gasoline. In fact, this would make the only legal fuel for aircraft 100LL in some areas of Canada.

Since there is a cost advantage to using automotive gasoline, some may continue to use it anyway. If the pilot owns an amateur-built aircraft, this is not illegal. In both cases, the pilot that uses GCE is in danger of becoming an accident statistic.

Before explaining why it may be dangerous to use GCE, let me state that it is possible to design an aircraft that can operate safely using it. The problem is that at the moment there are virtually no aircraft designed to run on GCE, whereas car companies have been designing cars to use it for years.

So what are the dangers?

  1. Fuel starvation
  2. Fuel leaks or fire
  3. Power loss or failure
  4. Reduced aircraft durability

What is the risk? I can’t state for sure what the potential risk is for any one aircraft. However, I would like to make an analogy to drunk driving: you may get away with drunk driving once or twice-some may get away with it every time-but, sooner or later most people end up in serious trouble. It is only a matter of time. It is just not the right thing to do because of the dangers involved.

I don’t have space in this article to define all the potential problems or tell you how to convert your amateur-built to use GCE, but here are some things you should consider if you decide to ignore the advice and use GCE anyway:

  • Ethanol is a great solvent that often attacks elastomers and dissolves sealants and sloshing compounds. It will dissolve old gasoline gums that may plug screens or filters. Therefore, introducing GCE may interrupt your fuel supply in several different ways-assuming your fuel doesn’t immediately start leaking. It took about an hour for a friend’s fuel tank to start leaking after he used GCE in his amateur-built.
  • Ethanol is corrosive to aluminum, terne-plate and galvanized steel under particular conditions. Aluminum needs to anodize in order to be free from corrosion.
  • Ethanol contains oxygen and will lean the engine. This can burn valves, blow pistons and cause power loss. Because it contains less energy, it needs higher fuel consumption for the same power, and therefore, may also require fuel-system modifications.
  • Ethanol can be extracted by water and lose octane as a result. The engine may detonate or suddenly stop if this happens.
  • When GCE is mixed with gasoline that does not contain ethanol, the vapor pressure increases to be greater than the separate fuels. Therefore, while separately the products may meet specifications, mixed together they may not. (This is why some cars may experience driveability problems if you switch from one type of gasoline to another.) In an aircraft, this could contribute to vapor lock problems.

So, hopefully, I’ve convinced you that the danger is real.

So, how do you protect yourself if you are not sure whether or not gasoline contains ethanol? Some companies, including the one I work for, will put a label on the GCE pump, stating the gasoline contains ethanol. However, this practice is not universal. Therefore, you should determine a reliable brand that you know does not contain ethanol, or will label it if it does. If you are in an area where most stations have ethanol, you should assume that others likely do too.

The safe practice is to test your gasoline to see if it contains ethanol. This is easy to do because adding water to a gasoline sample will extract the ethanol and increase the water phase volume. The test methods are shown in the box below. Safe and enjoyable flying!

Brian Kenny is a fuel quality expert with a major oil company. He is responsible for automotive and aviation fuel specifications. He owns and operates both an amateur-built and a certified aircraft with an STC for automotive gasoline use.

Test Methods for Determining the Presence of Alcohol in Fuel (Ref.: Airworthiness Manual Advisory 549) The two methods described here are equivalents. They are based on the property of alcohol to combine with water or ethylene glycol, and therefore, separate from gasoline. Alcohol fuels could damage fuel systems and engines, and therefore, should not be used. (a) Water method (1) Ina small-diameter transparetn cylinder, put approximately 10 mL of water, and clearly mark the level. (2) Add aproximately 100 mL of test fuel. (3) Shake vigorously, then let stand. (4) If, after settling, it is apparent that the water volume at the bottom has increaed, alcohol is present. (b) Ethyleme glycol method (1) In a small-diameter transparent cylinder, put approximately 100 mL of test fuel, and clearly mark the level. (2) Add approximately 10 mL of thyleme glycol. (3) Shake vigorously, then let stand. (4) If, after settling, it is apparent that the fuel volume at the bottom has decreased, alcohol is present.



Oh! Oh! What About the O-Rings?

On August 8, 2006, a Cessna 170 was conducting a full-stop landing at Fort McMurray, Alta., when the engine stopped and the aircraft had to be manually pushed off the runway. The owner had filled the tanks about three weeks prior to the incident. He had drained the tanks and got some water from the left tank. When he drained the right tank he didn’t realize that the contents in the sample tube were entirely water. Upon inspection, it was discovered that the right tank contained about a gallon of water. It was determined that the O-rings (gaskets) in the filler caps were unserviceable. Rainwater had most likely displaced the gasoline. This incident serves as a good reminder for aircraft maintenance engineers (AME) to carefully check the condition of the fuel cap seals anytime they perform an inspection, and for pilots to ensure that all the water is drained from the tanks when they do their walk around.

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