· Rotor blades
· Fly bar and paddles
· Tail rotor assembly
· Ball Links
· Linkages
· Pushrods
· Bell cranks
· End float on main shaft
· Main gear and associated mechanicals
· General security of mounting and retaining bolts
· Engine mounts
· Fuel tank
· Fuel and pressure tubing
· Exhaust system
· Tail boom
· Boom supports
· Undercarriage
· Canopy security/clearance
· Servo mountings and free play
· Security of avionics pack
· Aerials RX and TX
· Cable routing for chafing
· Main frames for cracks, wear and tear

Most of the above should be self-explanatory but I'll cover a few in more detail.

Rotor blades MUST be in good condition. Check for cracks and the integrity of any covering material you may have used. Look for cracks and signs of distress around the mounting bolt area. You DON'T want to lose a blade in flight as not only could it harm an individual, your helicopter will almost certainly destroy itself before your eyes due to the imbalance created. Tail rotor blades are just as important, but you can get away with the odd irregularity in the leading and trailing edges due to contact with long grass etc. Don't forget to balance the tail blades as well as the main blades, it just may cure that vibration problem you are having! Make sure the fly bar is straight as this is another source of vibration, and ensure the paddles are in line. You can buy alignment tools but there's not a lot wrong with the Mark One Eyeball!

The bearings in the tail rotor grips need to be checked on a regular basis. With the blades extended, check for side play. If present see if you can adjust it out by tightening the retaining bolts, if not, renew the bearings. If you tend to be a bit heavy with the tail on landings you will put the whole assembly under stress, which in extreme cases can lead to stripped main gears. Unless the tail gearbox is firmly bolted to the boom, it's possible that it could twist out of line and produce interesting handling characteristics! Whilst you're inspecting the tail assembly check that it's vertical.