What do you think of this? We just switched out our Mariner for a Beta 50 hours out of its 2200-hr overhaul. First picture was from the pre-flight, second was 0.8 later on the post-flight. Would you take the next student out for his flight? According to Robinson, the only requirement for oil in the tail rotor gearbox is that “oil should be visible in the sight glass.” After looking closer, you find several drops of oil on the bell crank. That change your answer?