RC India

So you have just had the worst luck, and the model is lying in pieces.  What do you look for in trying to figure out what went wrong ? 

How is the investigation different for electric versus nitro ?

BTW, there is no point in investigating when you know YOU caused the crash (by getting disoriented etc).  What we are looking for is the case when you THINK it is NOT your fault (yeah right !  how many times have we heard that one before !??!?!)

Step 1 :

I guess we should start with the split second when you sense something is wrong (which is even before the model has crashed).

The first thing is safety, trying to guage the amount of control, and directing the aircraft away from people and property (like cars).  If you are too close to the ground already, try to cut throttle (or hit "throttle hold", if you are flying a heli).  A spinning prop hitting the ground is much worse than an "unpowered" one doing it.

You have to verify what controls are still active, before crashing if possible.  The crash itself may cause additional parts failures, so having an understanding of what was working and what is not working greatly helps.  But we all know that this kind of "quick investigation" may not be possible in those critical moments, as we are already beginning to panic.

Pitch in folks ! What should you look for after the model is lying in front of you in pieces ?

The Money that just went pooof  ;D :D helping to reach 5 K

Glue would be a good thing if not too many pieces or a bag if too many pieces. ;D

Getting serious ok :

In majority of the case it is normally pilot error .

The other major contributor to this is the lack or interference in communication between the receiver and transmitter ,

If it is a control system failure I would basically look  at the linkage connections , have had incidents of  connectors coming off in air  if they  are fine then the next step is possible  loose connection at the receiver end of the servos .
If all that is fine  and there has been  a control surface malfunction  the I would investigate the BEC/ESC.

Checking the LIPO battery voltage will also be a practice to rule out battery failure.

Sai

As TG says a bag is the first thing to look for  ;) ;D ;D

Hate people with an "inverted" sense of humor ;D  Will not talk to you guys for many months  :-X  :-X  Unless of course, you say anything bad about Futaba, in which case I will speak again with lots of vengeance  >:(  >:(

Back to the list mode (I love putting things in lists, easy to refer to later on, and also for adding new stuff), and summarizing Sai's post :

1. Check if there is still movement in all the control surfaces.  This also validates if your radio link is still active.  Of course, assuming the main items are still connected to each other (receiver battery, receiver, ESC in the case of electrics etc).

2. Check which of the controls is not responding.  If any one is not responding, check if there was a loose connection.  Check for broken or "popped-out" servo arms, broken linkage rods etc.

3. Check if any electronic device is abnormally hot/melted etc.

4. If there are light indicators, note their statuses.

5. If you have a voltmeter, check voltages of the batteries involved.

6. Check if you were flying the right model, and if you had your antenna extended etc (for non 2.4).

7. For non-2.4, check if anyone just turned on their radio, or was setting up a new model (for synthesized sets).

8. Check if you had any control surfaces reversed (should have caught this in preflight checking).

How about:
a. Smell... tell tale sign of your motor winding/esc cooked
b. Lipo having taken a serious hit and some of the innards spilt... Alternately, the lipo could also be heating up on the verge of instability... not the time to be around !! Lithium catches fire when exposed directly to atmosphere!!
c. Motor mount... Nose hits with motor mounted on the nose ... watch out for breakage/weakening of the motor mount, shaft of the motor, circlip of the motor shaft, collar on the motor shaft, sand in between the rotor and the stator, loose magnet, loose motor mount fasteners. In case of clamped on motor mount, change of position or loss of downthrust and side thrust, loss of continuity of the windings, soldering broken etc.
d. Prop... if not broken, check for proper tracking. Improper tracking (both blades move in different paths) indicates a crack in the process... dangerous to use such a prop... could break in the middle of rotation at high speed and penetrate anything in its path like a missle.
e. Under-carriage... A tipping over tendency indicates that the under carriage is bent beyond the cg position

My half cent..this helps salvage parts but may not help find the cause of crash.

Don't pick or move your heli from the location where it kissed the ground before you analyse all damages.

It's a natural tendency to pick up the heli, 'cos you are already heart broken.

There could be parts lying nearby which you could salvage.

When I had my belt CP crash last(pilot error) on green grass, I didn't observe a lost linkage push rod, though I identified all other broken parts. It should've been a popped off link that lay somewhere near on the grass. I realised the linkage is missing only when I reached home. I had stored all spares except the linkages(I thought I had but I didn't).

Wish I had taken some patience and inspected thoroughly before leaving the crash site.

don't check the link (push-rod to horn on control surface) they often come out on impact.......

they will lead you on a wrong path..... :banghead:

What happened here ? :headscratch:

http://www.youtube.com/watch?v=8cUXf4HZdR8

"Wooaahh.... Unbelievable crash.. Unbelievable crash.."
Probably some 'invisible' wall!!  ;D

in my case, i would only look wether any parts can be reused............

wow, in the video the plane comes apart just from the aerodynamic stresses on the airframe - as the pilot pulls up too fast from a very high speed low pass. As gm said it sure lookes like it hit an invisible wall!
 reversed control surfaces, especially ailerons, is a common mistake.
Also in gassers vibration can easily  loosen bolts etc that are not locktited. 

http://www.youtube.com/watch?v=1cwmT5hmI3U