Aviation Safety Letter 4-2003

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Postby lazair » Tue Nov 11, 2003 6:58 am

Buying an Ultralight Airplane — Part 1

ALL REPRINTED FROM http://www.tc.gc.ca/civilaviation/syste ... 3/menu.htm AND THANK YOU TRANSPORT CANADA


by Inspector Martin Buissonneau, Recreational Aviation, Flight Training Standards, Transport Canada, Quebec Region


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Part 1
Since certified airplanes are often prohibitively expensive, many pilots are turning to ultralight airplanes to make an old dream come true or to explore a new passion. Here is a short guide to help you if you plan to buy an ultralight airplane.

What are your needs? What will be the main purpose of the airplane? For example, for some people, the airplane will be mostly used for local flight, while others will want to use it for cross-country flights. Your answer will help you define your needs. There are different types of ultralight airplanes: three-axis flight controls, similar to those found on a conventional airplane, powered hang gliders and powered parachutes.

Powered parachutes (and powered paragliders) are included in the category of ultralight airplanes. To fly this type of aircraft, you need a valid medical certificate and at least an ultralight airplane pilot's permit [Canadian Aviation Regulation (CAR) 401.03(1)], which may be restricted to powered parachutes. In addition, the airplane must be registered (CAR 202.13) just like any other ultralight airplane.

These three types of airplanes are flown in very different ways, and do not all require the same amount of physical effort. If you have always flown the same type of ultralight airplane and decide to buy a different type, it is highly recommended to get some in-flight training from an instructor who is experienced on the new type of airplane.

Here are some pointers that might help if you plan to buy your first ultralight airplane. They are not necessarily arranged in order of importance, and some of them are intended to make you think and do some research before you buy. This list is not exhaustive; other items could be added to it, and the items that have been mentioned could be expanded.

Airplane characteristics: general airplane performance, particularly on takeoff and landing (on hard or grass surface, etc.); hourly fuel consumption (some manufacturers now provide a chart showing the percentage of power used and the hourly fuel consumption at a given altitude); payload; crosswind limitations (you should take into account your ability to control the airplane in a crosswind because it may be lower than the airplane's capacity); manoeuverability in turbulence (relative to the airplane); good visibility (depending on your height); fewest possible blind spots; on-board stowage space for your personal effects; conventional or tricycle landing gear, depending on the terrain; possibility of installing floats, and availability of skis manufactured for the airplane in question (for use in snow-covered take-off and landing areas). If the ultralight airplane will be used for cross-country flights, an enclosed cockpit, or at least some protection from the elements, given Canada's climate, will increase your comfort and make it easier to use navigational charts. Also, with an airplane that has an enclosed cockpit, an adequate heating system will make it possible to fly in cold weather for a longer period of time. Another factor that should be taken into account, depending on the environment in which the flight will take place, is propeller and engine noise.

Power plant characteristics: engine reliability; ease of maintenance and availability of original parts; manufacturer-approved maintenance shop in the area where the airplane will be used; possibility of outfitting the airplane with a two- or four-stroke engine; dual ignition (and the safety it provides); a gear- or belt-driven reduction gear system; propeller (type of material used in construction, number and pitch of blades).

Other equipment: two-way radio, braking system, flaps, a strobe light that is clearly visible by other aircraft, and a ballistic parachute system.

Other considerations: You should consider storing the ultralight airplane in an enclosed hangar, protected from sunlight and bad weather. If you already have adequate shelter, check the interior dimensions to make sure that it will fit inside, before you buy the airplane. By the way, some ultralight airplanes come with folding wings. Since liability insurance is mandatory under CAR 606.02, it would be wise to read up on the terms and conditions of this kind of insurance before you buy. If you lack experience with the type of airplane you plan to buy, it is importantto get some training from an instructor who has experience with that type.

In Part II, we will discuss carrying passengers and whether to buy a new airplane or a used one. We suggest that you keep this article, as well as the second part, which will appear in the next issue of the Aviation Safety Letter, so that your checklist is complete.

Happy flying.
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Postby lazair » Tue Nov 11, 2003 6:59 am

Accident Reports
This section contains reports on accidents and incidents involving recreational aircraft. The purpose of these reports is to inform you about the circumstances that led some of our fellow pilots to deviate from their flight plan, in some cases with tragic results. The information provided here is based on reports published by the Transportation Safety Board.

British Columbia — Chinook Birdman — Always check the propeller drive belt for wear.
The aircraft appears to have stopped climbing at an altitude of about 200 ft, even though the engine throttle had been set to maximum power at takeoff. A forced landing followed, causing damage to the airframe. The pilot, who had logged only six hours of flying time since the start of the year, believes that the loss of pulling power from the propeller was caused by insufficient tension in the belt connecting it to the engine. This belt had been in service for seven years. During the pre-flight inspection, the pilot had checked this mechanism and found that he could displace this belt by about ? in. by applying 10 lbs of pressure at a specific point. After the forced landing, the pilot checked the belt's displacement again and found that it was between ¾ and 1 in. Rubber dust was visible under the lower pulley of the belt mechanism, indicating that the belt had been subjected to rubbing and premature wear. Once the aircraft had been brought back to the hangar and the propeller drive mechanism had cooled down, the belt tension was checked again, and the displacement had returned to ? in. In preceding flights, the ambient temperature had been low, which was surely what had prevented the belt from slipping in the drive pulley mechanism. Pilots of ultralight aircraft equipped with Rotax engines recommend that this belt be replaced approximately once every 8 to 10 years. The pilot in question has decided to replace this belt every two years from now on, as a safety precaution. After this incident, he said that he should have paid attention to the sound of his engine during takeoff, because the problem with the belt likely caused the engine to run louder than usual. If the pilot had noticed this noise, then cut the engine power back, he might have been able to keep flying longer and return to his departure point without incident. Inspector Pete Firlotte, of the Prairie and Northern Region, reminds readers that belts adjust themselves when necessary and sometimes sag and weaken with age, so that they can no longer do their job as well as before-just like some pilots. It is far better to replace a belt at regular intervals than to have to make a forced landing!

Quebec — Motorized paraglider — Unapproved modification
The student pilot had motorized his paraglider by adding an engine and propeller, but because the surface area of the paraglider wing was not designed for this additional weight, the aircraft became harder to control. An instructor who was making a pleasure flight in the area saw his student who, unbeknownst to him, was preparing to take off. A few minutes later, the instructor saw that the student had taken off and had put his aircraft into a spiral at an altitude far too low for this manoeuvre. The instructor made several attempts to contact the student by radio to advise him of the risk he was running and to tell him to land immediately, but in vain; the student pilot never responded. The aircraft crashed in a field not far from where it had taken off, and the student pilot did not survive the crash.
To build aircraft that meet very specific flight requirements, manufacturers spend thousands of hours designing and testing their components and systems. When you make modifications to your aircraft's structure or control systems, you run a high risk of compromising its structural integrity and your own safety. Your aircraft's flight characteristics are closely determined by its original components, and it can be dangerous or even fatal to modify them. If you do so, you and your aircraft become an experimental system, subject to all the difficulties that this entails. Do you really think that you are qualified to be a test pilot?

Alberta — RAF 2000 Gyroplane — Let's stick to approved manoeuvres!
The pilot had qualified as a gyroplane instructor and had logged many, many hours of flying time on this type of aircraft. He had assembled his new gyroplane himself and was about to make his first flight. The weather was clear, and the takeoff went without a hitch. After making a few manoeuvres in the airport circuit, the pilot decided to make a high-speed pass. At that precise moment, witnesses on the ground heard a muffled noise and saw the aircraft break apart in the air. The pilot lost his life. The cause of this accident is hard to determine, but the high-speed pass may have imposed an excessive load on the airframe, causing a major failure of its components. As you can see, in some cases, one overload is all it takes to cause an accident, even with a brand-new aircraft. So make sure to always comply with the manufacturer's specifications. How long has it been since you reviewed the flight manual for your aircraft? Can you state with assurance that you are familiar with all its contents? Do you perform a weight and balance analysis regularly, or only following a good scare?
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Postby lazair » Tue Nov 11, 2003 6:59 am

Stall-spin Accidents, Follow-up from ASL 1/2003
by Alain Gauthier, Engineer-Physicist and pilot

I read your publication very conscientiously and always find ample food for thought. The article Stall-Spin Accidents May Be Hazardous to Your Health caught my attention, and I would like to stress some aspects of it. All pilots, of course, have their own store of knowledge and experience, and they have to form their opinions from their own backgrounds and broaden their performance envelopes…but, if we do not study ourselves, nature will teach us by example.

Identical aircraft? An ideal… Certified aircraft are issued a type certificate. In theory, all such aircraft should be identical, but pilots know that every aircraft has its own personality at any given moment. In a critical flight situation, the smallest of these differences counts.

Wing condition: All industrial production tolerates a margin of error. Wings of the same type are therefore all slightly different. What is more, the average angle of incidence and dihedral are not necessarily identical on both the left and the right. Their weights also vary. And even if two aircraft were identical to begin with, their operating lives will change them in different ways (fatigue, overloads, turbulence, dirtiness of their lifting surfaces and so on).

And lift beyond — V2/2: Stalling occurs on the upper wing, reducing the lift component due to the Venturi effect, but increasing the angle of attack tends to increase the pressure on the lower wing. Total lift is therefore the algebraic sum of the forces on the bottom AND the top of the wing. The top may contribute as much as three quarters of the total lift, and, without its contribution, the aircraft cannot maintain steady level flight, unless it has the necessary power (F-18), and controlled flight becomes harder and harder to sustain.

Stall and spin: The rudder can help to maintain control in slow-flight or stall situations because it can speed up one wing and slow down the other. At the stall limit, therefore, kicking in rudder can restore lift on one wing while increasing stall even more on the other. The upshot is that the pilot has given the aircraft a very effective way to turn round on itself.

Speed and spin: Stall and spin certainly go hand in hand, but bear in mind that it is not the aircraft that stalls, but the wings. Here are two cases that are often linked.

First case: Like every Canadian pilot, I was initiated into spin. Demonstrating spin from VS is often not clear, because the controls are ineffective in this situation. To counter this, I begin in slow flight — about 1.2 VS — but I do not have to wait to stall. In the classic manoeuvre, yanking back the column and kicking in rudder produces a very clear stall on one wing while the other gains lift. The moral is that one stalled wing is enough to start to spin! So, I feel that spin is always lying in wait when turning on short final, virtually in slow flight, even if the aircraft has not stalled.

Second case: We were told again and again that you have to make shallow turns in the circuit, but…you gradually forget what you were taught about the load factor "g". I think it is important to explore our own performance envelope with our aircraft. During basic training, I learned to make 45° turns at 1.2 VS. The first time was somewhat daunting: it required a load factor of 1.41 g, and, at 1.2 VS, the limit is 1.44 g (not good at low altitude). Yet, some pilots attempt this manoeuvre at 100 m while turning on final…
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Postby lazair » Tue Nov 11, 2003 7:00 am

Medical Certificate-Ultralight Pilots
During recent investigations of a number of ultralight aircraft accidents, it was discovered that some pilots did not have a valid medical certificate. Ultralight pilots are required to hold a valid medical certificate when exercising the privileges of a flight permit. Medical certificates for ultralight pilots are valid for a 60-month period and must be renewed thereafter. As a reminder, the monetary penalty for a first offence is $1000; it increases with any subsequent offences. Holders of a pilot permit-ultralight aeroplane may renew their medical certificate by completing the medical declaration form located at the following Web site: http://www.tc.gc.ca/civilaviation/gener ... 6-0297.pdf and forwarding it to the nearest Transport Canada Civil Aviation office for processing. For more details, contact your regional Transport Canada office.
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Postby lazair » Tue Nov 11, 2003 7:00 am

Accident Statistics: Amateur-built, Ultralight Aeroplanes and General Aviation Aircraft
Accident statistics may be thought of as a measure of our ability as pilots to use our skills to conduct safe flights. Flying last year was safe — 3 730 000 hours of flying yielded an occurrence rate of only 26.9 for each 100 000 flying hours. The Transportation Safety Board (TSB) publishes yearly statistics on all modes of transportation in Canada, and it was pleased to report a decrease in occurrences for the year 2002. The level of flying activity did decrease by 3 percent, but a 1 percent drop in occurrences overall is significant. Can we do better? Yes, if we as pilots are diligent, serious, healthy, conscientious, intelligent and above all, safety-minded.

A lot of people wonder year to year about the accident rate for small aircraft. Many of them still revel at the thought of piloting their own aircraft, and who can blame them? We live in a world that allows us to leave behind all earthly bonds and enjoy the wonders and beauty of nature from a bird's eye view. I believe that almost everyone recognizes that it is somewhat of an engineering feat to apply and coordinate the multitude of distinct physiological and intellectual abilities to carry out a flight. However, it comes with the profession.

About half of the 139 occurrences involved privately operated aircraft, and of those, 13 were fatal. Flying schools and flying club aircraft are included in this calculation. Canadian-registered Ultralight aircraft accidents totalled 36, and of those, 9 were fatal in which 12 lives were lost.

What is the secret to safe flight? Ask yourself these questions: Could I do better with my flight planning? Am I in a rush each time I go flying? When was the last time I took a refresher course? Am I afraid to be tested by an instructor? Remember, safety is no accident; it must involve careful planning.
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Postby lazair » Tue Nov 11, 2003 7:01 am

Shoulder Harnesses Can Save Your Life
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One third of general aviation accidents deemed survivable end in fatalities because the pilot and passengers did not wear their shoulder harness. These accidents are usually caused by a loss of power, and occur most frequently during the take-off or landing phase. In many cases, the forces created at impact are insufficient to cause death. The fatality results when the body collides with the instrument panel or other parts of the cabin. It is distressing when you think that the simple use of a shoulder- and lap-belt assembly could considerably reduce the risk of fatalities.

Most people will agree that the lap belt is important during takeoff and landing and when there is an encounter with turbulence, but few recognize the importance of wearing the shoulder belt during the most dangerous phases of flight-takeoff and landing. Wearing the shoulder belt is the best insurance against injury should there be an abrupt end to the flight. Every aircraft should have shoulder harnesses installed. It is just as important as having an airworthy aircraft. You should inspect them for wear regularly and ensure that they always function properly. Check the fabric of the belts regularly, especially where it contacts the metal guides and metal locking mechanisms, and forward the assembly to the manufacturer for repairs at the slightest hint of tear or a frayed section. Any damaged area will reduce the assembly's design strength and may be responsible for serious injury in case of a mishap. As pilot-in-command, make sure that the preflight checklist requires that the crew and passengers have their shoulder harness fastened before takeoff and landing. If your aircraft does not have shoulder harnesses, you should have them installed as soon as possible. They do not interfere in any way with your duties, but are the best insurance policy you can have in case of an accident. Be safe — always.
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Postby lazair » Tue Nov 11, 2003 7:02 am

COPA Corner: Why Do a Walk Around?
by Adam Hunt, Canadian Owners and Pilots Association (COPA)

I recently received a question from some low time pilots. They reported several observed instances where experienced pilots have jumped into their plane and flown away without doing pre-flight inspection. They wondered if pre-flights are something worth doing, or if they are just exercises for student pilots?

Of course most of the time the aircraft has sat, untouched, since its last flight. But an oil leak may have developed, or someone may have done some "hangar rash" to the plane. In some cases, a thief may have siphoned out all the fuel, except a few litres. That could be a surprise on take-off! Pilots have taken off with external control locks in place, or with concrete blocks tied to the tail. It is very important to do a complete pre-flight inspection before every flight.

One of the most important times to do a careful pre-flight inspection is when the aircraft has been through maintenance or when it has just been reassembled after being transported. This story shows just how wrong things can go, for lack of a pre-flight inspection. The worst thing is that the same accident has been repeated more than once, always with the same fatal results.

Even though this story involves a particular aircraft type, the Pterodactyl Ascender ultralight aircraft, the lesson learned is universal. These car-top transportable aircraft are often kept at home and then assembled prior to flight at the airport.
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There were original manufacturer's investigations following up the official investigations of several early 1980s accidents where a leading edge spar failed in flight, with no other aircraft components failing. In all cases the results were fatal. The official investigations listed these accidents as "Undetermined", but the follow-up factory investigations found the answers. In each case the spar failed just outboard of the inboard spar sleeve junction, where the inner set of rigging cables joins the spar. The spar failed upwards and twisted as it failed, giving a very distinctive signature to the failure.

These spar failures all had the same signatures and the same causes-the inboard compression strut had failed to do its job. Each wing has two compression struts. The compression struts are designed to keep the front and rear tubular spars apart and also to take the wing's inter-spar compressional forces. Without the inboard compression strut in place, both spars will move together until one breaks. The rear spar is prevented from moving forward by the hang cage centering cable, so the front spar is the one that fails.

There are several reasons why the compression strut can fail to do its job. The compression strut mounting brackets, the bolts or the compression strut itself could fail. There are no recorded instances of the failure of any of these parts. In all accidents investigated, the parts mentioned above were undamaged. The most likely reason for these accidents is that the compression strut was not secured during assembly of the aircraft.

Pterodactyl Ascender ultralights are designed for quick disassembly and reassembly and the compression strut is provided in two parts, joined by a sliding bolt lock. If the two compression strut parts are not connected during assembly, or the bolt lock is not slid into place, the result will be a spar failure in flight. The requirement to check this item is clearly outlined in the Pterodactyl Builder's Manual. The Pterodactyl wing sail is provided with four zippers for just this pre-flight item.

The key defence against these kinds of spar failures is a good pre-flight inspection. Special care should be taken to inspect these after the aircraft has been re-assembled or has undergone maintenance affecting the compression strut area.

Your aircraft doesn't have to have "quick disconnect" style compression struts to have critical pre-flight inspection items. All aircraft have items related to control locks, tie-downs, fuel, oil and other fluids plus many damage-sensitive, structural and control-related areas that must be inspected before each flight.

Do you really need a pre-flight inspection before you fly any type of aircraft? You bet your life you do!
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