Aircraft Oil Weight - Viscosity Viscosity is the measure of the oil's resistance to shear or flow. High viscosity indicates a high resistance to flow while low indicates a low resistance. It varies with temperature and is affected by pressure.
Increasing temperature causes viscosity to decrease; conversely reducing temperature causes viscosity to increase. Higher pressure causes viscosity to increase which also increases the oil's film thickness. Viscosity is measured by shear and time. When measured by shear it is expressed in centipoise and is known as dynamic viscosity.
Aircraft Oil Weight
Kinematic viscosity is expressed in centistokes and is usually given at two temperatures 40 C and 100 C. Kinematic viscosity is measured as the time required for an oil sample to flow through a viscosity tube at a standard temperature.
Rate Of Turn
This value is then converted to centistokes. The radius of turn is a function of the airplane's speed. Greater weight means higher speed. And, higher speed means an increased turn radius. If you are instrument flying, the radius of turn can be crucial when flying procedures accurately.
Lubricants provide a fluid barrier between moving parts to prevent friction and wear. As for cooling, oil provides up to 40 percent of an aircraft's air-cooled engine's cooling. Oil creates a seal between piston rings and cylinder walls.
This helps to reduce wear, provide better compression, and keep contaminants out while improving fuel efficiency. If you have an oil filter, be sure to change it at every oil change. It is especially important to cut open the old filter and inspect the element for metal.
If you ever spot an uncut oil filter in the trash can at your maintenance shop, find yourself another shop! Straight mineral oil contains no dispersant and is usually recommended by manufacturers for the first 50-hour break-in period on new or newly overhauled engines.
Mean Aerodynamic Chord
It allows faster piston ring seating and allows the accumulation of some advantageous deposits which lead to better oil loss control. SAE standards for lubricating oils include J1966 and J1899. The SAE standard J1966 establishes the requirements for nondispersant, (straight grade) mineral lubricating oils used in four-stroke cycle piston aircraft engines.
It covers the same requirements as the former military specification MIL-L-6082. J1899 establishes the requirements for lubricating oils containing ashless dispersant additives, the same as MIL-L-22851. This term uses a straight line drawn through the wing to express the center of gravity.
It is given as a percentage, with the wing's leading edge being 0% and the trailing edge being 100%. You can read more about chord lines here. If your airplane flies at least once a week, or if you operate in a low-corrosion environment such as the desert or the mountains, you probably don't have to worry too much about corrosion.
This is especially true if the airplane is also hangared. In this case, we recommend that you use a multi-weight oil such as Phillips 20W-50 or Aeroshell 15W-50. The Aeroshell semi-synthetic is a slightly better lubricant, while the Phillips X/C is slightly better at cleansing.
So Which Oil Should I Use?
Both are excellent choices. Fully synthetic oil such as Mobil AV-1 (no longer available) is a multi-vis synthetic oil with an AD additive package similar to other AD oils. Synthetic oil has better lubricity (or slipperiness) than petroleum-based oil, as well as several other advantages.
Unlike petroleum products, a fully synthetic oil does not carbonize (or "coke") under high heat, nor does it lose its viscosity with prolonged use. "Second choice: Aeroshell W 80 or equivalent SAE 40 ashless dispersant aircraft engine oil.
Use should be limited to climates with typical ground level engine starting temperatures of not less than 10 F, nor more than 90 F. Semi-synthetic oil such as Aeroshell 15W-50 is a blend of multi-vis petroleum-based oil with fully synthetic oil (in the case of the Aeroshell product, it's a 50-50 mix).
Such a blend is an attempt to combine the excellent lubricating properties of a synthetic oil with the excellent cleansing properties of a petroleum oil. For the most part, it achieves these goals. Aeroshell 15W-50 is an excellent oil which does almost everything well.
Multi-Grade Oil
However, like all multi-weight oils, it remains quite thin at room temperatures, and so strips off engine parts readily and leaves them vulnerable to corrosion during periods of disuse. About a year ago, Shell started adding a new corrosion inhibitor to the additive package of Aeroshell 15W-50 in an attempt to remedy this problem.
However, we feel that it's too early to tell just how effective this new additive is. "Third choice: Anti-wear formulation Aeroshell 15W-50. Use may be indicated by typical flight operations to and from climate extremes such as southern USA to Canada or Alaska where winter ground level engine starting temperatures would be below 10 F.
Empty Weight Empty weight is defined as the total weight of an aircraft including all fixed ballast, usable fuel, undrainable oil, total quantity of engine coolant and total quantity of hydraulic fluid, and excluding crew, payload, usable fuel and drainable oil.
Oil. Its basic functions within an engine include reducing friction, cooling, sealing, cleaning, and serving as protection for moving parts. But it's often taken for granted. This article will look at the basics of lubrication and the various types and characteristics of oil.
Does Empty Weight Include Unusable Fuel?
If the volume goes up, that means the mass is divided by a greater number, making the density less. While you may not think this is significant, a relatively minor temperature change can make all the difference.
This is especially true when lifting large volumes of liquids. Maintenance So whether you choose a single-grade or a multigrade, straight or an ashless dispersant make sure the oil change intervals are maintained according to manufacturer recommendations.
Also consider the aircraft type, engine type, and the flight profile to help determine the correct oil for the environment and application. This will help ensure the oil you're using performs to the standard required. If you were flying behind a turbine engine, the choice of oil would be easy.
You'd simply choose the slipperiest, longest lasting lubricant you could find, and that would be a 100% synthetic oil. End of story. If you operate in a temperate climate (such as is found in much of California), you can use single-weight oil all year around.
How Many Gallons Of Jet Fuel Does A Hold?
However, if you operate in sub-freezing winter temperatures, then we recommend that you switch to a multi-weight oil during the cold-weather months, and then return to single-weight oil during the remainder of the year. (If your mechanic tells you that it's bad to switch from one type of oil to another, he's misinformed.)
Let's start with a look at the most famous of jets, the Boeing 747. The Boeing website states that this model, with a gas tank capacity of 63,500 gallons, can burn five gallons of jet fuel per mile of flight.
As for medium crude, the weight of the oil in a 55-gallon drum will be somewhere between 399 lbs and 414.7 lbs based on the Louisiana DNR standard. Including the drum, that's between 439 and 454.7 lbs per drum.
Heavy crude oil will weigh over 421.85 lbs, and West Canadian Select will weigh about 425.46 lbs. Finally, the last category of additives is anti-wear and anti-corrosion additives. Oils such as Exxon Elite 20W50, Aeroshell 15W50, Aeroshell W100Plus, and Phillips 66 100AW include varying combinations of anti-wear and/or anti-corrosive additives.
How Much Does A Gallon Drum Of Oil Weigh?
That said, products such as ASL CamGuard and AVblend can be added directly to non-additive oils such as Phillips 66 X/C 20W50. In these times when airplanes are flying less, I recommend using some sort of anti-corrosion additive in your oil.
Please note that these are both FAA-approved additives. You should never use an unapproved additive, regardless of what you might hear around the hangar water cooler. Jeff Simon is an A&P mechanic, pilot, and aircraft owner.
He has spent the last 14 years promoting owner-assisted aircraft maintenance as a columnist for several major aviation publications and through his how-to DVD series: The Educated Owner. Jeff is also the creator of SocialFlight, the free mobile app and website that maps over 5,000 aviation events happening throughout North America.
Free apps available for iPhone, iPad and Android, and on the Web at www.SocialFlight.com. That covers the flow characteristics of the oil, but what about additives? The first and most important type of additives is ashless dispersants (AD).
How Is Aircraft Fuel Weight Calculated?
Ashless dispersant oils have an additive in them to aid in scavenging debris and carrying it to the filter or screen. This is a very important quality, given the relatively high wear of aircraft engines and the amount of combustion acids and other contaminants that get past the cylinder rings and valves.
If oil is doing its job, it should be dirty. Oil treated with an effective dispersant suspends dirt, metallic materials, and unburned carbon. By monitoring an oil's condition through oil analysis you can establish operating trends to use it as a preventive maintenance tool.
Check with the engine manufacturer's recommendations, but the typical oil change interval rule of thumb is 50 hours for a filtered engine, and 25 hours if it is a screened engine. Along with the hourly interval, oil should be changed on a quarterly or seasonal basis.
This process will help eliminate moisture from the engine and oil to help prevent corrosion. To fly safely, the aircraft must be balanced and loaded correctly. Imagine if, before every flight, you had to weigh everything onboard.
Moment Arm
Fortunately, we don't have to do this. Why? Because we use standard weights when calculating aircraft weight and balance. Today we will talk you through how aircraft loads are calculated, explain the general concept, and discuss factors that affect aircraft weight and balance.
Subtract the total amount of fuel you have on takeoff from the amount you will use during your flight. What will be your takeoff fuel weight? To calculate your takeoff fuel weight, multiply your takeoff gallons by the weight of fuel.
Aviation engines have used a different viscosity rating than that of automotive and SAE. They use 65 weight or SAE 30, 80 weight or SAE 40, 100 weight or SAE 50, and 120 weight or SAE 60. Aviation multigrades developed later adopted the SAE automotive system of classification and can be found in 15W-50, 20W-50
, and 25W-60 ranges. Additives Oil quality is determined by refining processes, but additives can improve overall performance. Additives, usually new technology brought to the market through multigrades, can include anti-corrosion, high load, and anti-scuffing characteristics.
Standard Weights In Aviation – Why Do We Use Them?
They can dramatically improve the performance of lubricants in older technology engines. Multigrade oil Multigrade oils are either full mineral-based oil or a synthetic blend. Multigrades are primarily designed around all-season operation and convenience. They meet the requirements of more than one SAE viscosity grade classification, and are therefore more suitable for use over a wider temperature range than a single-grade oil.
Multigrade oils contain viscosity improvers that reduce the tendency of an oil to lose viscosity or thin out at different viscosities. Other benefits include lower oil consumption and better fuel economy. But when it comes to the piston engines that power our airplanes, the issues are much more complex.
That's because the oil in a piston engine is called upon to do a lot more than simply lubricate. The oil must also serve as a coolant, a cleanser, an acid neutralizer, a sealant, a hydraulic fluid, and a preservative.
Finding an oil that performs all of these functions adequately well can be a tricky business. When selecting oil, the first thing to consider is viscosity. Simply put, "viscosity" is the measure of a fluid's resistance to flow.
Final Thoughts
Most air-cooled aircraft engines are designed for SAE 50-weight oil at operating temperature (approximately 210 degrees Fahrenheit). An arbitrary 'line' is used as a point of reference for weight and balance measurements. When looking at an airplane load sheet, constant reference will be made to the 'datum'.
This is normally defined by the airplane operator, and you'll typically be able to find out where the datum is in the airplane flight manual (AFM). Single or monograde Monograde oil is a petroleum-based lubricant with a single viscosity grade.
Single-grade oils are considered by some to be better for warmer temperatures, but can't provide the flow needed for cold start-ups without the use of a heated hangar or engine preheating devices. In some locations one viscosity can be used throughout the year.
On the other hand, if you are based in a corrosive environment—within 100 miles of the coast, the Gulf, the Great Lakes, or a major metropolitan area with its industrial pollution—and if your airplane sometimes goes for two weeks or more at
Single-Grade Oil
a time without being flown, internal corrosion should be a major concern. This is especially true if the aircraft is not hangared. If you fall into this category, we strongly suggest that you use a single-weight AD oil such as Aeroshell W 100 to provide the best possible protection against corrosion during periods of disuse.
A moment arm is a fancy aviation term to describe a pivot and lever. The pivot is normally the center of gravity. The lever is a force that an aerodynamic surface (usually the tailplane) applies. It works according to Archimedes' law.
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