Removing cowlings, spark plugs, etc.
I would say that being able to swap out a spark plug would probably be the most frequent or likely Mx problem that could be resolved by a pilot/owner with minimum tools and spares.
Aeroplanes have an uncanny way of knowing what will be the least convenient thing.
I lost a starter motor in arguably the most remote airfield in the world, CYEU Eureka, in temperatures of -40°.
Tools they had. A spare Aztec starter motor not so much.
Had I not had a spare, I would have had to abandon the aircraft there. There is no way I could have hand started it in those conditions.
…but I think that a tyre might still be the thing most likely to ground you, if it is shredded.
Yes; good point. I have known a few TBM/KA pilots who permanently kept a spare tyre in the nose luggage compartment.
However, can you change a tyre yourself (if you can borrow jacks etc)? I wouldn’t know how to.
Peter wrote:
can you change a tyre yourself (if you can borrow jacks etc)? I wouldn’t know how to
I think my point is that you are very much more likely to be able to do it if you have a tyre 
I would contact either my own engineers or someone else, and get talked through it. Jacks can be borrowed or improvised. You could probably use a car jack, with great care.
Peter wrote:
However, can you change a tyre yourself (if you can borrow jacks etc)?
I’m the only one who has installed tires on my planes during my ownership. In the field, I’d first look for somebody else to help especially since I don’t carry a spare.
Spark plugs Vs spare tire: me thinks bad plugs are far easier to deal with than a flat tire and takes less tools and space/weight.
That said, having a tire & tube on board when in remote locals would be a close second.
Michael wrote:
Compressed air – What for ?
Blowing stuff out. For example getting the remnants of the old grease out of wheel bearings etc.
Peter wrote:
However, can you change a tyre yourself (if you can borrow jacks etc)? I wouldn’t know how to.
Cleveland have a complete service manual for their wheels and brakes you can download as a PDF onto your mobile device, they have the complete procedure for changing tyres.
Peter wrote:
However, can you change a tyre yourself (if you can borrow jacks etc)? I wouldn’t know how to.
That’s not too hard. Perhaps you should store the AC 43.13-1B on an iPad? Together with the maintenance manual of your aircraft. The advantage is, it doesn’t weigh anything.
Some planes can win by taking some stuff to set up a more advantageous CG, the LA-4 for instance is known for being too fast out of forward CG (… I have even “installed” capacity for 40(!) liters water in jerry cans in the rear baggage compartment to set up the CG), so weight doesn’t need to be an issue. Same goes for the DA40, I was surprised how fast that bird is out of trim.
