The pressure Bulkhead is vertical with A DOOR. The Rear stairs when down and locked Prevent the Plane from sitting on its tail. That's a Fair summary, there. Compressor stalls happen to the centre Engine when strong cross winds were there on take of at Rotation and at night will Light up the aerodrome for a few Hundred yards and everyone on Board will KNOW something's Happened. The centre engine is Less efficient, because of the 'S' Duct. Lot's of redundancy with the B 727. Synchronous Electric system Ground Power. APU and 3 Generators with constant speed drives. In Those days a Twin engined Plane was quite restricted what Routes it could be operated on so operators used 3 o4 engined Planes. Normal fuel consumption was 10,600 Lbs /hour on the stretched 200 Series which was considerably trickier to Land than the Earlier 100.'s. Powerful hydraulic controls Gave very good control in rough approaches, where often quite a lot of Power from the engines was required.. I spent Just over 13 Years on them all up. No Engine failures but a few systems failures. Not due to the design or my operating skills. Got Marooned on Xmas Island once with an Engine Fuel control "O" ring failure which cost 37,000 $'s to have another flown from Perth. IF I have a Favourite Plane the B727 would be IT. Nev