“Where’s the access for the oil drain?”
“Down there. You have to reach past the engine mount, around the back of the supercharger, don’t hit the whatsis, and don’t forget to cut off the safety wire before you try to remove the drain plug. Hanging upside-down helps.”
Except that it’s hard to remember which is right and left when you are half-inverted on the work platform, trying to get to everything while the oil is still warm enough to drain quickly. I really, really disliked the designer who put that thing there.
Oh, and you have to replace the safety wire, which has to go around the plug in a certain way, and be twisted in a certain direction. If you don’t twist the wire tail and bend it so that the end is smooth and blunt, the Crew Chief or next person to work in that area will have WORDS with you. Trusssssst me on this.
I think every airplane and almost every other type of vehicle has one of those things – something you can’t get to easily, or quickly, or that is in a compartment so tightly crammed with expensive and fragile stuff that you are afraid to breathe and more afraid of dropping a hand tool or the gizmo you are trying to troubleshoot/repair/replace. Hellholes are found on all large aircraft, and someone always has to put the battery waaaaaay back in the tail-cone for weight-and-balance purposes. Unless the battery is just in a place that requires removing part of the interior of the plane to get to. Not an easy part, either.
Merlin engines and other in-line designs are infamous, because the designers made as tight a package as possible in order to squeeze everything into a very streamlined design. Trying to get to the starter, or oil drain, or certain other accessories takes slender hands, long arms, and bones like Plastic Man or Gumby. I once looked at a Japanese engine that appeared to have been draped with spaghetti or linguini. All the wires for the spark plugs, all running down the outside of the engine, and getting in the way of, well, finding anything else.
Electronics bays are notorious. Many jets and some turboprops put the guts of the electronic stuff, back in the pre-solid-state days, or when the plane has a radar unit on-board, up front in the nose near the oxygen tanks*. You cannot get to this bay from the cockpit. You have a separate hatch that opens into a dark, cramped, and either hotter than the blazes or colder than a well digger’s hip pocket space that is about as wide as most men’s shoulders. OK, not that cozy, but it feels like when you are trying to do any work in there that requires more than “remove box, slide in new box, close hatch.” Granted, airline-sized planes do have more room, but it’s still dark, and too warm or too cold, and when you drop things, they fall farther. I can pretty much guarantee that the more expensive the [thing], the louder it sounds when it hits the cement, no matter the size of the thing or how many steps on the ladder it hits on the way down.
I have had the privilege of squeezing myself into electronics bays, tail cones, wing roots, and aft fuselages of a number of aircraft. It was fun, and were I still that limber, I’d do it again. But I’d wear much better ear protection.
*In some biz-jets, the emergency oxygen bottles are in the nose. As you pre-flight the plane, you check the bottles, open the valves, and remove a long red “remove before flight” streamer that flaps outside the O2 compartment like a tongue. If the plane is taxiing “with its tongue out,” you’d better park, shut down, get out, and turn on your emergency O2 system. There’s some suspicion about a certain biz-jet crash and the bottles getting overlooked during preflight. Nothing is proven, though, but the super-long crimson streamer stems from that time.