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Spitfire Restoration

August 15, 2017

 

 

Spitfire Restoration Project honours South African Spitfire   pilots

The Spitfire Restoration Project recently hosted ten Spitfire pilots at the South African Air Force Museum at AFB Swartkop. The project, to restore the Museum’s Supermarine Spitfire Mk IXe, ‘Spirit of Reutech’, which was badly damaged during an emergency landing in April 2000, is being managed by the Friends of the South African Air Force Museum (FSAAFM).

 

The gathering reunited South African Spitfire pilots who flew these remarkable warbirds in the Second World War, or afterwards in air forces such as the SAAF. According to Ian Grace, chairman of the Spitfire Restoration Project steering committee, there are around 20 Spitfire pilots in South Africa, and the Friends managed to get 10 of them together for the reunion, where the fuselage section of the Museum’s Spitfire was on display. 

“The enthusiasm for the Spitfire shown by these pilots, most of whom are in their nineties, was remarkable. It was an emotional and inspiring day for all of us. They were profuse in their thanks for letting them join in what was, for them, such a special event,” says Grace. “Our thanks to the SAAF Museum and to the staff at AFB Swartkop, who went out of their way to help us in setting up the event, and to everyone else who made it such a fantastic day.”

The Museum Spitfire restoration is a tribute to all who have served within the SAAF, both as support and aircrew. The Project will create awareness of aviation history, the history of the SAAF and the rich legacy of the Spitfire to younger generations. 

The Friends of the SAAF Museum lobbied to have the Spitfire Mk IXe returned to at least static display condition, and the SAAF Museum Council has approved this, giving the Friends the management responsibility for the project. Since then, most of the work has gone into setting up the correct project organisation, structure and plans to provide a framework to do that.

However, Grace is hoping to take the restoration a step further, and is “keen to get Spitfire 5518 back to flying condition to promote the Air Force and aviation amongst the youth.”

For more information on the Spitfire Restoration Project and how you can help, go to www.spitfire-restoration.co.za

 

KNOW YOUR PLANE - Wyndham Ferreira – Ferreira Aviation Bloemfontein

The Importance of Oil Changes

Oil may be expensive, but we have often heard that AMOs say regular oil changes are the least expensive maintenance an aircraft owner can carry out on his aircraft engine. Aircraft engine manufacturers have very strict guidelines as to when oil changes should be done, which include calendar time limits, even if the engine has run less than the recommended hour requirements. 

The lubricating oil in your engine has six major functions and must perform all of them simultaneously – and without any compromise. 

These six functions are:

To provide a cushion between moving parts

Reduce friction between moving parts

Protect the highly finished internal parts of the engine from corrosion

Keep the interior of the engine clean and free of sludge, dirt, varnish and other harmful contaminants

Provide cooling to internal areas

Help seal the piston rings to cylinder walls 

Let’s look at each function in more detail.

 

A CUSHION BETWEEN MOVING PARTS 

Severe loads are imposed, not only on the valve train, but within the cylinders, crankcase and accessory drive section. Parts are being thrust open, yanked shut, spun on static bearings and so on. We can only imagine how long these parts would last if it was not for the thin layer of lubricating oil between them. 

 

REDUCING FRICTION 

Lubricating oil is distributed to the moving parts of the engine in a number of different ways. This oil reduces friction by having an effect similar to millions of tiny ball bearings rolling around between the moving parts. The little ‘ball bearings’ of the engine oil vary in size depending on the different viscosities or grades of aircraft engine oil. It is thus important that the correct type of oil is used.

 

PROTECTING INTERNAL PARTS 

After engine shutdown, a coating of oil covers the entire interior of the engine. This coating provides protection against corrosion. However, the oil drains off after time, exposing the interior of the engine to corrosion damage. Over time, contaminants get in the oil, for example combustion gasses that get past the piston rings, which cause the oil to become saturated with corrosive agents. However, there are additives which provide protection against corrosion during normal operation of the engine.

 

CLEANING THE INTERIOR 

Ashless dispersant oil (e.g. Shell W100, Shell W100 Plus) keeps your engine clean by using additives that cause the dirt to disperse throughout the oil and prevent it from precipitating out of the oil and collecting in the engine when the oil is at rest. This is a very important function, since the many oil passages could become clogged with dirt and cause oil starvation. Hydraulic lifters need clean oil to work properly, otherwise they clog with dirt and sludge and cease to carry out their very important function. 

 

COOLING 

Moving parts generate friction, which in turn produces heat. Lubricating oil eliminates metal to metal contact, and the constant flow of oil to all these moving parts carries away the heat. The cylinder head, for example, is exposed to extreme temperatures during normal combustion. Engine oil, the cooling fins, engine baffling and so on, all remove excessive heat from these areas. 

 

SEALING 

A thin film of oil on the cylinder walls not only lubricates, but helps provide the necessary combustion gas seal between the piston rings and cylinder walls. A complete gas-tight seal between the rings and walls is never completely attained, so the oil is subjected to high pressure and temperature blow-by, allowing hot contaminated gasses to pass the piston rings into the crankcase of the engine. 

 

DIRT CONTAMINATED OIL 

It is evident that while the engine lubricating oil in your engine is carrying out all of these functions, it is subjected to a vast number of demands. Apart from the internal corrosion, dirty and worn out oil is a major contributing factor to engine wear. 

Modern day high compression engines subject the lubricating oil to severe stresses. The oils undergo a continuous sheaving action from many of the moving parts in the engine. In time, the sheaving action will alter the oil’s original viscosity. Once this happens to the oil, its continued use will lead to a reduction in the life of the engine.  

As the oil flows through the engine carrying out its many functions, it collects heat. The oil temperature on the instrument panel is normally oil leaving the oil cooler – after it has been cooled down. It is therefore fair to make the assumption that the actual oil temperatures are much higher during the course of its operation. These high temperatures subject the oil to coking and oxidation. Coking dirties the oil with carbon particles, while oxidation causes the oil to break down and thicken. 

A filter will remove much of the coking but nothing can be done about the oxidation. Both of these effects cause harmful destruction to the oil, and if this oil is left to continue operation past the manufacturers’ recommendations, you are asking for big trouble. 

Low oil temperature is also harmful to engines because burning-off harmful acids will not happen at low temperatures. A good rule of thumb is to have an oil temperature higher than 180°F in cruise. 

During normal operation, the engine continuously adds more contaminants to the oil. Not only does the blow-by past the piston rings contribute to the oxidation, but it also contaminates the oil with various acids and corrosive salts generated during combustion. Some of these contaminants cannot be removed by the filter and in time the oil becomes saturated with corrosive agents.

Water vapour forms each time the engine is started or shut down. Fuel dilution occurs during starting and, when all the pollutants get mixed up in your lubricating oil, it forms sludge, varnish and highly corrosive acids. 

Acids are particularly harmful when they get wet or contain water. Your precious engine, even in a low humidity Highveld hangar, standing for two weeks or more, is subject to these damaging agents wreaking havoc with the inner parts of your investment. 

The only way these poisons can be dumped is by regular use – getting the oil to operating temperature (180°F and above) and drying the oil out, so to speak. Obviously, the more humidity the greater the problem. It is also for this reason that manufacturers call for calendar based oil change periods. 

It is important to note that corrosion on the interior parts of your engine starts within days of shut down. I strongly recommend that aircraft be flown at least every two weeks to get the oil up to operating temperature to burn off contaminants. Simply ground running the engine will in most cases not get the oil temperature to 180°F and ground running aircraft engines is also detrimental. 

Should an aircraft engine be out of service for longer than a month, the manufacturers’ engine inhibiting instructions should be followed. 

Although we would like to think our aircraft engine air filter installations are of the same standard as a Toyota Land Cruiser Donaldson filter with snorkel installation, this is definitely not the case – in fact, it is a far cry from it. While starting up, taxiing and even during flying, not to mention the typical dusty conditions we find in some parts of our country, dirty air passes through most of these flimsy installations, causing havoc to your engine. Regular air filter maintenance cannot be over-emphasized. I clean my Bonnie and 182’s filter every time after I’ve used a gravel airstrip. 

 

WHEN DO WE CHANGE? 

The aircraft manufacturers give the oil change frequency instructions and this should at least be followed. My experience is that if you have a spin-on filter installed and fly less than 50 hours per year, change the oil every 25 hours or 4-6 months, whichever occurs first. If you fly 100 hours or more per year, a 50-hour oil change is recommended. Without a spin-on oil filter, change the oil every 25 hours or 4-6 months, whichever occurs first. I change my aircraft oil every 25 hours or 4 months, irrespective of installations. Proper air filter and induction maintenance should also be carried out at this time.

 

WHAT TYPE OF OIL? 

There are basically two types of oil: A mineral base straight oil and the ashless dispersant oil. Oil type, viscosity and of course different brands, is a discussion on its own. 

Mineral base straight oils are mostly used on all aircraft engines during the running in period, although Lycoming does not recommend the use of straight mineral oil on the turbo charged Lycoming engines. Ashless dispersant oils will generally be used after engine run in because it has additives that collect dust, assists with corrosion prevention etc. Ashless type oils are available in different viscosities. Refer to the engine manufacturer for the recommendations. 

Different brands of oil, for example BP and Aeroshell may be mixed when topping up if your regular oil is not available, only if they are of the same viscosity. For example, A Shell W100 SAE50 ashless may be mixed with another brand of ashless SAE50. Although some manufacturers recommend that you can mix a multi-grade with a mono-grade, I do not recommend that. Maybe I am from the old school, but if your engine has been running on a type and specific brand of oil, stick to just that until TBO. 

 

SUMMARY 

Operating in dusty areas, cold climates, infrequent flights and long idle periods will require more frequent oil changes than recommended. It is imperative – and still one of the cheaper maintenance actions  that can be carried out on your engine that will save you thousands in the long run. Fly your aircraft frequently and keep the filters and oil fresh.

 

 

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