You have to find it
Another cowl strike... and this one bears a similar factor from a previous cowl strike that I discussed and posted pictures of. you can read that previous post by clicking here...
Here is a redacted bit of an event report. It is a current event. Who did it, where it happened, etc. is much less important than NOT DOING IT AGAIN...
While slowing to land on top of the hospital rooftop pad, the flight
medic riding in the passenger compartment stated "That wasn't me," and
said he had heard a noise. The pilot nor the flight nurse on board had
The pilot landed the helicopter on the rooftop pad, unloaded the
patient and crew and then proceeded to the hospital hanger to refuel
and return the helicopter to a mission ready status.
Further investigation revealed a hole approximately 20 wide by 8
high on the number 2, (Right Side), hydraulics cover/cowling. It was
determined that a dzus fastener on the forward portion of the
hydraulics cover either failed or was not fully fastened and loosened
to a point where it allowed the hydraulics cover to flap freely and
come in contact with the turning rotor blades.
All 4 rotor blades had minor scratches and the hydraulics cover was
replaced altogether. No other damages occurred.
There is much to be thankful for here. First of all and most importantly, no one got hurt. Second, the aircraft was not destroyed. Make no mistake though, this is going to be costly. When the manufacturer is consulted about the "scratches" on the blades (and the operator most certainly will consult, they will not assume the liability for operating equipment with any known damage such as this) the manufacturer is going to direct replacement of all "scratched" blades. They make money by selling blades you know, and they are wickedly expensive. I wouldn't be surprised if they call it a sudden-stoppage event and also direct replacement of rotor hub and transmission. I wish I didn't know about things like this but from personal experience I do.
Sidebar: Operator to manufacturer phone call... "Hey we had this little event happen and we need to know what to do." "Well, just do this, do that, buff it out and drive on." "Hey great! Can you send us that in writing?" "Ohhhh, if you want it in writing, well then you need to replace etc. etc. etc." No one takes a chance when it's in writing...
So, what are the lessons to be learned...
1. Do a thorough walk around before each and every flight. Don't just confirm that the latches are latched.
One of them is open - you have to find it.
The pilot should owe the crew a prize (pizza?) if they can catch him or her leaving a "dzus" or any other type of latch, catch, cap, or cowl undone. All crewmembers should be taught how all forms of latch work, and what they look like open, closed, and in-between.
2. Emphasis added... DON'T IGNORE A STRANGE SOUND. If a crewmember says, "hey I heard something (or smelled something or saw something) different you must stop and investigate... complacency makes us overlook warning signs and continue, at our peril...
The one chance to obtain Situational Awareness is often lost because we are tired and something small arises. It's like a whisper that something is wrong. If your aircraft does something different stop and figure it out. This same type of mistake, when someone noticed something and it was not acted on, has led to many damaging events... like the one in my previous post in which a crewmember heard a "ticking' sound but they took off anyway.
"There are no new causes of accidents...it's new people making the same mistakes..."