Biggest student I ever had was 6 foot 10 and weighed 350 pounds. He could check the fuel on a C 172 by just leaning over the front of the wing while still standing on the ground
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He could only fly the aircraft fitted the optional articulating seats which he placed full down and all the way back on the seat rail safety stops. We also had to put a case of oil in the baggage compartment to keep with in the C of G limits.