Before you do anything else, just relax. I can assure you that you are not the first person to crash, no matter how bad it looks. Also, this will not be your last! Hopefully you remembered to hit "throttle cut" or at least "throttle hold" before your heli hit, but if not and the engine is still running, shut it down as quickly as possible. If the transmitter will not stop it and it's safe to approach, meaning you don't have to do the Funky Chicken to get there, walk up and close or plug the exhaust. Plugging the exhaust is a much better way to execute an emergency stop than trying to pull off the fuel line. Next, take a minute to regain your composure; as long as no one was hurt, everything else can be repaired and all is well.
Crash Site Clean Up
The first thing to do is look around very carefully, as it's usually very difficult to re-locate the crash point to search for any missing parts. Carefully pick up everything, turn off your receiver, drain any remaining fuel, and then carefully pack up your heli for transport home. Yes, I know you might want to just throw it in the back of your truck, but trust me, you'll feel different in a little while.
Determine The Cause
Now that you have calmed down a bit and the heli has been safely recovered, try to think about exactly what happened. I find that most crashes fall into one of three categories:
1) Impossible-to-preventmechanical failure
If we are honest, with today's helis this is a very rare occurrence.
2) Preventable mechanical failure
This happens much more often; there is no substitute for proper maintenance and pre-flight checks.
3) Dumb Thumbs (Pilot error)
I find this third category has two sub-categories: Misjudgment (less room or time that you thought) and loss of orientation (too much of the wrong input).
In order to prevent the exact same accident in the future, first you must understand what caused this crash. Remember there are a few crashes in which the real cause is never found. If this is the case, check and double check every item on your heli, including your transmitter.
If you have a second or backup heli, and if it's safe to do so, fly it! Even if it's just for a few minutes of easy flight, you will be surprised how much better you'll feel. If not, repair your heli quickly and get back in the air. There's nothing worse than sitting around dwelling on the crash for weeks, wondering if you should try again.
1) Get back to flying with your backup heli or your repaired heli as soon as possible.
2) If in doubt about any item, have it checked, or replace it.
3) Keep a crash kit on hand for your heli so you won't be waiting for the needed parts.
4) Take this opportunity to completely service your heli; for example, re-pack bearings.
Don'ts:
1) Don't feel like you're the only person who crashes.
2) Don't rush the inspection or rebuilding process.
3) Don't be tempted to use questionable parts to save time or money, as it won't do either.
4) Don't be afraid to ask for help, it's only a few keystrokes away at http://pg-rc-fliers.blogspot.com/
Heli Autopsy
Carefully start disassembling your heli, being careful not to do more damage in the process. It's very easy to put extra strain on servo wires and gears while you are tearing things apart. Take your time, inspect, and carefully clean each part as you remove it.
INSPECTION
Two things that can be difficult to see are slightly bent parts and cracked parts. Today's modern composite materials are very strong and light, but they can hide small cracks completely.
Apply a reasonable amount of pressure to all plastic parts while looking for cracks. During inspection of a mainframe following a crash, I was certain it was okay to reuse, but after giving it a gentle twist I found a crack through an important area. The last thing you want is a second crash on your next flight because you overlooked something.
FIND AND REPLACE
At this point it becomes obvious that certain items will need to be replaced. These usually include the main blades, fly bar, tail boom, and main shaft. This is not to say these items are always damaged, or these will be the only parts damaged. It is also very common for any or all of the shafts to be bent, and it is very important to carefully check and replace those that are damaged. Flying a heli with bent or damaged shafts can cause considerably more damage, and can cause another crash.
There are many ways to check a shaft's straightness. If a shaft is already removed from the heli due to crash damage, the easiest method is to simply roll it on a hard flat surface. I have a piece of glass I picked up from a local glass shop free of charge as a scrap. About a 1 foot square works well, it's best if it's " or thicker. If the shaft is straight it will roll very easily without any noticeable shakes or wobbles. Remember there's no such thing as close, it's either straight or needs to be replaced. The most common shafts to bend in a crash are the main shaft, the feathering spindle, and the tail rotor shafts. If your model is equipped with a clutch/start shaft (like Hirobo models) then re-check your clutch shaft alignment. If, on the other hand, the crash wasn't bad enough for a complete disassembly, I have found it possible to check most shafts with a dial gauge while they're still in place.
Check and Double Check
Carefully check ALL wires, connectors, batteries, and servo and gyro cases looking for any signs of damage. If any damage is found, have the item checked and repaired, or replace it. Serious damage or injury can occur if damaged parts are used, and it will end up costing you more in the long run.
Like a Phoenix from the Ashes
Now that we have checked everything and replaced all the damaged items, it's a matter of re-building the heli according to the original assembly manual. Follow the entire manual, even if you did not disassemble a particular item. Remember to double-check everything, and if you have an experienced friend, ask them to check it over.
Now let's go to the field and get flying again. Treat this heli just like new, it will most likely need to be re-trimmed. Give it a single careful flight, listening and watching closely, land immediately if things don't sound or look right. If all goes well, take it to the pits, remove the canopy, and give it a thorough check.
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