Abstract: A tank suitable for holding a lubricant is provided with a dipstick. A sleeve which is mounted on the tank and adapted to support the dipstick is interconnected with the output duct of the tank by means of a further duct. The arrangement is such that if the dipstick is incorrectly located in the sleeve, air is permitted to flow through the further duct into the output duct so that the pressure of the lubricant in the output duct is reduced. This pressure reduction consequently provides an indication of incorrect dipstick location.

Abstract: An oil tank suitable for an aircraft mounted gas turbine engine is divided into three series connected chambers. Aerated oil after engine use is fed into the first chamber and de-aerated oil withdrawn from the third chamber for engine use. The chambers are interconnected in such a manner that when the tank is inverted, a reservoir of oil is retained within the third chamber to provide a continued supply of oil to the oil outlet for a finite time period and insufficient oil flows into the first chamber from the second to obstruct an air vent provided in the first chamber.