Aircraft engine oil tanks, lubrication systems, and associated methods are provided. The oil tank includes a first tank portion defining a first volume for holding oil and a second tank portion defining a second volume for holding oil, in fluid communication with the first volume. The first tank portion includes an oil outlet for delivering oil to a lubrication load via a pump. The first volume is in fluid communication with a vent opening for venting the oil tank. At least part of the second tank portion is disposed higher than the vent opening for retaining a quantity of oil inside the oil tank during a negative-g force flight condition and facilitate the recovery of the lubrication system following the negative-g force flight condition.

A transmission oil sump comprises a main oil compartment, in which a suction line of an oil pump is located, and a secondary oil compartment. The secondary oil compartment is in fluid communication with the main oil compartment via an opening. To prevent the introduction of air during rapid acceleration, cornering at high speeds and/or rapid deceleration of the vehicle, a barrier closes the opening to prevent the flow of oil out of the main oil compartment into the secondary oil compartment so that the oil level, required for the oil pump in the main compartment, remains adequately high. When not closed, the opening of the secondary oil compartment is open to ensure oil flow from the secondary oil compartment to the main oil compartment. The secondary oil compartments is arranged so as to collect oil that leaks from transmission components.

Aircraft engine oil tanks, lubrication systems, and associated methods are provided. The oil tank includes a first tank portion defining a first volume for holding oil and a second tank portion defining a second volume for holding oil, in fluid communication with the first volume. The first tank portion includes an oil outlet for delivering oil to a lubrication load via a pump. The first volume is in fluid communication with a vent opening for venting the oil tank. At least part of the second tank portion is disposed higher than the vent opening for retaining a quantity of oil inside the oil tank during a negative-g force flight condition and facilitate the recovery of the lubrication system following the negative-g force flight condition.