Use of Aluminum:
Lighter than steel
Changes with heat more than steel
Good ability to transfer heat
Parts of uneven thickness heat and cool unevenly causing stress. This stress will weaken and eventually crack given enough time. This stress can be reduced by slowly heating and cooling engine
Engine History
(AC No: 20-105B 6/15/98)
The history of engine operation reveals that there has been little change in the causes of small single and multi-engine aircraft engine failures over the past forty years. 51% of all engine failures are directly related to pilot error related to preflight, inspection, or use of controls. Training programs could have prevented 70% of all engine failure accidents for pilots, mechanics, and trend monitoring.
The J-3 Cub, and an Aeronca Champ, had the same Continental engine.,. This engine was later modified from 65HP to 100 HP and became the O-200 found in Cessna 150's. the O-200 is a carbureted engine with the carburetor below the engine in front of the oil tank. This keeps the induction system cool and allows a little more power because of the cooler air in the cylinders. It also makes carburetor icing more likely. Flying behind a small Continental requires the application of full carburetor heat before throttle reduction.
In the sixties, Piper came out with a trainer modified from the Tri-Pacer series. This "Colt" had a Lycoming four cylinder engine. Lycoming engines had the camshaft above the crankshaft instead of beneath it like the Continental. This allowed a large oil pan on the bottom of the engine. By running the induction system right through the middle of the hot oil in the pan it let the engine to run a little cooler. An additional benefit was that it heated the air/fuel mixture. With Lycoming engines, you don't need use carburetor heat overtime.. The POHs said to add carb heat only if there was some sign of icing. The Lycomings are in all later Piper models. Piper pilots were occasionally surprised by icing when they failed to add carb heat on downwind.
All modern training aircraft use the Lycoming engine. The Cessna 150 was changed to the Cessna 152 to note the engine change. The early C-172's used the Continental O-300 which is a spin off of the O-200 in the C-150 with two more cylinders. It also has the ice problem of the O-200. The Lycoming C-172's do not have ice problems.
Pilot Training
--Use of operating manuals with emphasis on fuel management, power settings, carburetor heat and systems design, location and controls.
--Adherence to operational instructions, placards and limitations
--Use of checklists during normal and emergency situations.
---Recurrent training related to replacement parts, airworthiness directives and technical publications.
--The correct use of the primer must be a part of all checkouts and instruction. The primer pumps fuel to one or more cylinders in un-vaporized liquid. Failure to set and lock the primer is a frequent cause of a rough engine and engine damage. A cracked primer O-ring can have the same effect even with the primer locked.
--The correct care of tires and oleo struts must be a part of all checkouts and instruction. The oleo strut is a combined cylinder of oil and air. The air is compressible while the oil is not. Both of these are sealed at the top by an air valve and filler cap and from below by a rubber O-ring. If the exposed part of the oleo strut is not cleaned prior to every flight the accumulation of dirt and grit will be ground into the O-ring. In a relative short time the O-ring will be unable to seal either the air or the oil and the strut will deliver any landing or taxiing shock directly to the aircraft structure. No maintenance program can overcome the destructive expenses of a poor checkout or pilot training programs. Raising the costs of rentals can never keep up with the costs of poor piloting.
Preflight Neglect
1. Know total usable fuel aboard. Ignore unusable fuel.
2. Check and sump drain tank for proper color, debris, feel and liquidity.
3. Check vents especially fuel cap vents.
4. Confirm operation of fuel selector in off position as well as for fuel flow for selected tanks (Four minutes run time).
Fuel problems
1. Water due to condensation, filler caps, rain, and service personnel.
2. Wrong type or octane fuel.
3. Bladder tanks with defects.
Item:
A dead battery will show that you are out of fuel.
Fueling
1. Know exactly how much fuel you have prior to departure.
2. Know exact consumption rate
3. Know time in tanks
4. Develop fuel performance chart
5. Always plan to land with at least minimum reserves.
Grounding is a procedure to prevent the flow of electricity that is capable of producing sparks capable of igniting fuel. By grounding at least three minutes prior to refueling you give electricity time to balance the charge between the aircraft and the fuel service be it truck or pump makes no difference.. Once the balance is achieved the flow of fuel will not change the electrical equilibrium. When fueling over the wing be sure to touch the nozzle to an unpainted part of the fuel cap PRIOR to opening the cap.
Difficulties are simple and easy to understand. Prevention of occurrence is not so easy. Running out of fuel is not an expected event. The pilot is usually very much aware of the situation but lacks the mental discipline to choose a safe option.
1. Misinformation
POH numbers for capacity, consumption, fueling
2. Mismanagement
Tank selection errors, fuel caps, sump leaks,
3. Mechanical difficulty
Fuel pump, leak in pump, selector, electric pump, bladder problem or gauge problem.
Survival rate after engine failure is 94%.
Maintenance related accidents are only 20% of total.
Two planes a week run out of fuel.
Not refueling when the opportunity exists is viewed by the FAA as careless operation.
Fuel Weight:
--At 32-degrees F gasoline weighs5.93 pounds per gallon.
--At 97s-degrees F gasoline weights 5.7 pounds per gallon
--Buy your fuel when it's cold.
--Prime as hard as you can to vaporize cold fuel into the manifold system.
Engine TBO (Time Before Overhaul )
An aircraft engine that is flown non-commercially can be operated beyond the TBO recommended by the manufacturer. Once the choice is made a program of regular oil analysis should be in place. Oil analysis will give trend indication on engine wear and type of wear. The bottom end of the engine, consisting of crankshaft, camshaft, bearings and gears can be monitored by oil analysis. The top end, consisting of cylinders and their components are monitored by both oil analysis and compression checks.
1. Exceeding TBO will accelerate wear.
2. Part 121 and 135 operations cannot exceed TBO
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