A recent safety report regarding fuel and oil caps being left off or loose prior to a flight as brought this issue to light. On no less than three occasions the oil cap was found to be left off and the student found strapped in and ready to go - instructor intervention has prevented this from becoming an incident / accident. I am sure that there have been other occasions where the dipstick has not been inserted correctly and that mere luck has kept the dip stick from moving out during the flight allowing oil to escape from the engine.
If oil escapes through the filler cap or dipstick openings it will normally fall to the bottom of the cowling and blow out underneath the aircraft. The decreasing amount of oil in the system will mean that oil temperatures rise, as less oil is doing the same amount of lubrication. This would not normally be noticed a pilot on a training exercise as the oil temperature is fluctuating any way with the changing work load on the engine as training maneuvers are conducted. Thus the first a pilot will know of the problem is when the oil falls to a level where engine oil pump begins to suck air and is unable to maintain oil pressure.
It is the Pilots responsibility to check this prior to flight! This being said SAFETY is EVERYONES RESPONSIBILITY! This is the underlying foundation of safety in all operations.
Regardless of whom the ultimate responsibility lies, we should ensure that fuel and oil caps are secured and dip stick correctly fitted at all times. If you are required to put oil in an aircraft then make sure you play your part in the "Safety Chain" and leave the aircraft ready for flight despite what you may have been told by the pilot. If he or she forgets to check, then at least you have them covered and have prevented an incident. Be proactive ... tell them they forgot to check!
Students are students and they will forget or mess up. So if it is a learner pilot, make sure the instructor has checked prior to allowing the student to get airborne.
Make sure you don't leave Safety Traps for others to fall into!
Do you have any thing to add? Feel free to comment.