I was practicing for an upcoming job, a bridge inspection. Completely excited about how my big fancy new drone, with its super high-powered, top mounted gimbal camera would perform.  In previous tests, the upward obstacle avoidance system worked great although I noticed that while underneath the bridge wind conditions such as updrafts and turbulence were greatly enhanced and I wondered if my 2.5 meter buffer zone would be adequate.

I set out to simulate, as best I could imagine, the circumstances for my upcoming week, a bridge inspection over water.  I located the tallest bridge structure over a river in my county and proceeded to that destination.

Weather conditions were mostly sunny, light and variable winds 7-10 mph and 65 F.

After testing 2 controllers on the same aircraft and how they work together I proceeded to my main objective, which was to get pictures of the anchor bolts on top of the column caps.  Paramount to the success of this mission is the upward gimbal and the Z 30 zoom capabilities.  The difficulty, however, is getting high enough under the bridge with obstacle avoidance stopping me at 2.5 meters and turbulent wind pushing the aircraft around…all of that and take pictures too… hmmm. I could feel some apprehension coming on.

Preflight checklist…ok,

GPS… on,

camera settings… check.

Ready for take off!

Since we’re doing a bridge inspection there is not a lot of ground to cover, however we are looking for the details and current condition of the concrete. Whether the concrete has any places of delamination or “Spalling” and cracking at critical points of contact where anchor bolts protrude and/ or rebar may be exposed and an overall condition of the structure.

As I lift off the ground, I stepped over to a spot where I can clearly see the flight path, the bridge and the entire area where the mission will take place. After taking several “practice” shots and determining the camera is working correctly; pans, tilts etc., I proceed under the bridge. First shot, close ups of the drainage ports. With the Z30 camera mounted on the upward gimbal – no problem, tap –to- zoom, click, click, click- done. On to the next, the main purpose of the mission- anchor bolts. I fly further under the bridge to see the bolts on the column caps and the bearing plates. I found that the obstacle avoidance system keeps me from getting too high and tangling props with the bottom of the bridge. That’s good. So I back off and zoom in, this actually allows me to see the bolts, bearings and spacers, but not the top of the cap. This is a problem. The engineers will want to see the condition of the cap. My super cadence controller and crystal sky monitor is vibrating, so I fly out from under the bridge so I can look down at the monitor without the distraction of turbulent air. I stopped 6-8 feet outside- just out of the turbulence, to hover, see what the monitor is telling me and to ponder the possibility of getting higher, maybe between the girders.

My moment of pontification was suddenly interrupted by this obnoxious noise, the sound of something grinding against concrete. I looked up to see my state of the art carbon fiber aircraft plummeting into the river below. Evidently, that gentle 7-10 mph wind I mentioned earlier had pushed the 210 into the bridge. So much for obstacle avoidance. I really tried to stay calm, but was overcome with adrenaline. I ran to the riverbank, decided to set my controller down and with no thought of personal safety or wellbeing, I jumped over the edge into a briar patch. Fortunately, (?) I found the now limp scraps of plastic hanging in a bush. Only one arm and the extremely expensive Z30 camera were in the water. But what a break- only 8 inches of water! Ignoring all the cuts, scrapes, torn skin and clothing, I proceeded to pull all pieces out of the water and the bushes. Making two trips and having to pull myself up the banks with vines that were looking very much like poison ivy.

Back at the car I piece together the broken aircraft trying to account for any major missing parts. – Oh yeah, the controller! I left it down stream, better go get that.

OK, insurance is a good thing, and I’m completely covered.

But what a mess! Only 1 propeller and the landing gear survived. When I put the Z30 on the table and opened the SD card slot a shocking amount of water poured out. My insurance agent is not going to have a happy Monday!

In all of this, the really crazy thing I can’t figure out is the report from the manufacturer.

‘the aircraft wasn’t moving and there was no failure in the obstacle avoidance system’… OK so apparently obstacle avoidance doesn’t account for a breeze.

Lesson Learned!

One other mind boggling aspect, they refused to give me new propellers! My insurance settlement paid almost full amount for a replacement aircraft. I was on the phone with the third level up supervisor and the repair dept. They absolutely refused to include a set of propellers. I told them they needed to review their customer service policies.

And, by the way… those vines… WERE poison ivy…  worst case I’ve ever had!

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