Go Back  PPRuNe Forums > Aircrew Forums > Rotorheads
Reload this Page >

Fatal Crash Broome 4th July 2020

Rotorheads A haven for helicopter professionals to discuss the things that affect them

Fatal Crash Broome 4th July 2020

Old 11th Jul 2020, 10:37
  #21 (permalink)  
 
Join Date: May 2002
Location: Wanaka, NZ
Posts: 2,234
Originally Posted by blakmax View Post
...but I am curious to know if it is possible to differentiate between MRB vibrations and TR vibrations?
Yes, easy to differentiate between the two. A TR vibration is high frequency felt in the pedals. A MRB vibration is not high frequency and is not felt in the pedals.
gulliBell is online now  
Old 11th Jul 2020, 10:39
  #22 (permalink)  
 
Join Date: May 2002
Location: Wanaka, NZ
Posts: 2,234
Originally Posted by industry insider View Post
..A simple dynamic balance for the reported problem doesnít seem like the correct maintenance action.
I agree with all of that.
gulliBell is online now  
Old 11th Jul 2020, 11:24
  #23 (permalink)  
 
Join Date: Apr 2000
Location: EGDC
Posts: 8,046
FED
How else are you going to do it?
A hover track and balance would be a good start.

If they don't do that on Robbies then the pilot should at least have done a hover check and handling check without pax since he had previously felt the vibration and would instantly know if it was still there.

The old adage of 'If you think Flight Safety is expensive, try having an accident' seems to hold here - very sadly. All for the sake of a check test flight it would appear.

Perhaps he was satisfied that the problem had been reported, the engineers had done some engineering and signed it off so therefore it must be OK...............
crab@SAAvn.co.uk is offline  
Old 12th Jul 2020, 04:38
  #24 (permalink)  
 
Join Date: Sep 2006
Location: Inside the Industry
Posts: 812
Crab

If they don't do that on Robbies then the pilot should at least have done a hover check and handling check without pax since he had previously felt the vibration and would instantly know if it was still there.
I agree, although the failure may still have happened, but the pilot would have been the sole occupant. A vibration, noise or anything strange from the back end of a helicopter that isn't a simple TR vibe issue warrants a grounding and a thorough investigation before next flight in my view.
industry insider is offline  
Old 12th Jul 2020, 12:41
  #25 (permalink)  
 
Join Date: Mar 2007
Location: Hobe Sound, Florida
Posts: 751
GB: Yes, easy to differentiate between the two. A TR vibration is high frequency felt in the pedals. A MRB vibration is not high frequency and is not felt in the pedals.

Yes ....and possibly not. Not all main rotor induced vibes are 1P. Example: 4P main rotor on the S-70 is 17.6 hz while the tail rotor 1P is 19.8 hz. Hard to differentiate those two frequencies. It would help if only the pedals were shaking, but thats not always the case. The vib gear eliminates the doubt.
JohnDixson is offline  
Old 12th Jul 2020, 13:02
  #26 (permalink)  
 
Join Date: Aug 2019
Location: USA
Posts: 16
As a owner of new R44 this is very concerning to me. I believe that complying with FAA AD for checking cracks in TR blades would not have prevented this from happening. Looking at the pictures it looks like TR blade separation was secondary to something else. Very curious to find out the final conclusion by ATSB.
Since the owner of the company/helicopter himself perished in the accident I do not believe that neglected maintenance to save few bucks would have been an issue. What else a pilot can do other than report discrepancy to mechanic and go flying when he/she says everything is good.
BTW the date of AD is May 2020 and mine has completion date by manufacturer as June 19 2020. I am hoping they not only complied with AD but installed the blades with corrected design

Last edited by kansarasc; 12th Jul 2020 at 14:00.
kansarasc is offline  
Old 12th Jul 2020, 13:10
  #27 (permalink)  
 
Join Date: Oct 2006
Location: USA
Posts: 406
Originally Posted by industry insider View Post
. A vibration, noise or anything strange from the back end of a helicopter that isn't a simple TR vibe issue warrants a grounding and a thorough investigation before next flight in my view.
Has any info come out that says the vibration was still present after the maintenance was performed? Or was the vibration corrected by maintenance then the failure happened?
wrench1 is offline  
Old 12th Jul 2020, 13:20
  #28 (permalink)  
 
Join Date: Oct 2006
Location: USA
Posts: 406
Originally Posted by kansarasc View Post
What else a pilot can do other than report discrepancy to mechanic and go flying when he/she says everything is good.
Depends. Personally, I wouldn't release the aircraft without knowing what was causing the vibration. But if the vibration was corrected by the engineers, i.e., no vibration felt prior to this flight, then one would assume the disc was fixed. Until we know this part, it will remain a guessing game. Some seemingly routine discrepancies end up leading to unforeseen failures, like in one case where a random xsmn chip light led to the loss of the upper xsmn case and rotor system in flight. No one saw that coming either.
wrench1 is offline  
Old 12th Jul 2020, 14:02
  #29 (permalink)  
 
Join Date: Jun 2016
Location: Brantisvogan
Posts: 695
Originally Posted by kansarasc View Post
Since the owner of the company/helicopter himself perished in the accident I do not believe that neglected maintenance to save few buck would have been an issue. What else a pilot can do other than report discrepancy to mechanic and go flying when he/she says everything is good.
According to the report he had sold the business and was finishing a year of agreed service as part of the sale.

If an aircraft develops such a sudden and severe anomaly in the tail, it warrants a thorough inspection.
It will be a tough sell convincing anyone that a quick ground balance check meets that requirement.
That it all ended in tears soon after the first takeoff doesn't instil confidence that end-to-end checks were thorough enough.
It remains to be seen if the aircraft was actually flight tested subsequently or was just signed off on a nod and a wink.
Bell_ringer is offline  
Old 12th Jul 2020, 14:07
  #30 (permalink)  
 
Join Date: Oct 2006
Location: UK
Posts: 4,949
no vibration felt prior to this flight, then one would assume the disc was fixed.
He could well have done a vibration check in the hover before he departed and found it satisfactory. We will never know until one of the survivors recalls what happened.
Fareastdriver is offline  
Old 12th Jul 2020, 14:15
  #31 (permalink)  
 
Join Date: Nov 2009
Location: global
Posts: 27
You are right JD. There are a plethora of vibes in helos. Often a cause of much confusion. If anybody would like a "quick & dirty" have look a the link......it may help. Work you way down through the full gambit of helo vibes on the page and see if it helps:

https://www.rwas.com.au/rtb/?preview...a&preview=true
ring gear is offline  
Old 12th Jul 2020, 14:36
  #32 (permalink)  
 
Join Date: Mar 2007
Location: Hobe Sound, Florida
Posts: 751
RG, thanks, but a message saying I was not allowed to view drafts was all that presented itself. No worries: I had 39 years of chasing vibrations of all sorts. Unless you have discovered and are absolutely certain of the source, and confirmed that it cannot mutate to something more serious, it is a subject not to be put off.
JohnDixson is offline  
Old 12th Jul 2020, 16:57
  #33 (permalink)  
 
Join Date: Mar 2016
Location: US
Posts: 134
To my mind, it is unimagineable that multiple people reported unusual vibrations and it would seem a cause was not determined yet they continued to fly the aircraft. The investigation will of course find if this is the case or not. To suggest that it was a company with a good record, that they did a ground run with their balancer and found no vibration seems to belie any good practices that may have happened here. If, it turns out that they performed in flight track and balance, well, that mitigates my issue with this but even if so, a vibration with no obvious cause is just the kind of thing that pops up when people talk about how important safety is.

In 35 years of working on helicopters, of all sorts, I have seen several instances where the time was spent, the money was spent and the company bore the brunt of inconvenience to figure out wtf was going on when a pilot comment might have been as vague as " it just feels different". On some occasions it was something innocous like a loose piece of equipment ( not that that would always be innocous) but on several other occasions it was a hair raising discovery, resulting in copious amounts of beer and pats on the back after it was discovered and fixed.

Needles to say ( although apparently not really), it appears that something other than an assumed out of track or balance t/r was at work here but the assumption may have been made akin to " well, it can't be anything else and running on the ground is the same as running in flight" (not). Sometimes it takes an adamant pilot willing to risk their employment but wishing to fly another day, a mechanic who has time on their hands and likes a puzzle or an owner/operator who "gets it". Whatever it takes, doing the right thing is better than pieces flying around and the misery of an accident. This seems like one of those accidents that will ultimately have a well defined cause and explanation and I hope I am wrong about what "may" have happened here.
roscoe1 is offline  
Old 12th Jul 2020, 17:04
  #34 (permalink)  
 
Join Date: Aug 2019
Location: USA
Posts: 16
Originally Posted by roscoe1 View Post

but on several other occasions it was a hair raising discovery, resulting in copious amounts of beer and pats on the back after it was discovered and fixed.

.
Examples ? specifically for R44
just curious as a new owner to look for hidden monsters
kansarasc is offline  
Old 12th Jul 2020, 17:28
  #35 (permalink)  
 
Join Date: Mar 2016
Location: US
Posts: 134
Not too much on R22 during my time working on them. One cracked t/r flex plate just aft of clutch sheave, pilot noted clutch engagement time had changed by a couple of seconds. Might have been normal belt stretch but it made me look. Multipe sticking exhaust valves found over time, found due to change in mag drop, ignored by some, reported by one. Both were many moons ago.
roscoe1 is offline  
Old 13th Jul 2020, 16:29
  #36 (permalink)  
 
Join Date: Nov 2007
Location: Massachusetts
Age: 63
Posts: 167
Originally Posted by roscoe1 View Post
Sometimes it takes an adamant pilot willing to risk their employment but wishing to fly another day.
Reminds me of the day I was walking through our shop and was talking with one of the guys about a customer machine ( R44 ) he was working on. He had a component of the rotor head apart ( I'm trying to be a bit vague here on purpose ) and I mentioned my surprise that a particular part had a tapered bolt in it. I couldn't see any reason such a part would be designed that way. I was informed that it was not supposed to be tapered, it had just worn that way! 50% of the bolt was missing at the most worn position.

The story is that the ( young, probably first real job ) pilot complained about the flying characteristics, his company flew in a couple of ( A Star ) mechanics who looked it over and gave it a clean bill of health. The pilot, junior as he was, was smart enough to demand someone with extensive experience in type look at the ship, thus our involvement and discovery of the worn component.

There's no doubt in my mind that the bolt failing would probably have been fatal. I was, and still am impressed that the junior pilot would stand up to the company on that issue. A lot of people, especially at the start of a career, are not going to push back when a couple mechanics have declared a machine safe to fly.

He probably saved his own life, or the next guy who flew that machine.


Paul Cantrell is offline  
Old 13th Jul 2020, 17:46
  #37 (permalink)  
 
Join Date: Nov 2007
Location: Massachusetts
Age: 63
Posts: 167
Originally Posted by kansarasc View Post
Since the owner of the company/helicopter himself perished in the accident I do not believe that neglected maintenance to save few bucks would have been an issue. What else a pilot can do other than report discrepancy to mechanic and go flying when he/she says everything is good.
I disagree with both of these statements. Look, nobody is going to dispatch a machine they know is going to crash. But people have an amazing ability to rationalize situations so that they can tell themselves that although it isn't right, that it will be okay. Owners can be the worst in this sense, because they tend to be the one hurt economically when the machine is grounded, but pilots and mechanics are guilty as well. We pilots want to go flying! And vibrations are the worst because we can be more or less sensitive to vibrations on different days ( like on windy days versus smooth days ). And vibrations, while arguably the hardest to quantify, can also be indicative of the most dangerous problems. A blade that can be balanced but is soon vibrating again can be indicative of a cracked blade. Vibrations from transmissions... Well that doesn't even need to be mentioned how serious that can be. And yet, what do all helicopters do? Vibrate! It can be difficult to determine which are the normal vibrations, and which are indicative of the problem that is about to kill you.

What else can a pilot do when they feel something isn't right, but the mechanic says it's fine? Lots ( depending on your situation ). I've called both Bell and Robinson myself when I've been unsatisfied with what the maintenance people are telling me. The technical support people can give you ideas about what might be wrong, as well as things you might try to further diagnose the problem. Also, having a senior person with lots of time in type fly it can help validate ( or repudiate ) what you think you're feeling. I'm not talking about the local CFI although they can be helpful, I'm talking someone with over a thousand hours in type... They can often pick up on smaller anomalies that a less experienced pilot won't.

I was flying with one client in an R44 and I could tell there was a subtle engine problem... we were pulling just a little too much power and there was a tiny but detectable torque kick in the hover. I told them to get it checked, but the maintenance shop said there wasnít a problem. The next time I flew it, the problem was worse, but they still couldnít feel what I was feeling. I told them to take it back to the shop and insist that the shop look further. Sure enough an exhaust valve was sticking. Nothing that would take you out of the air, but the point is that someone with a lot of time in type will be able to detect things ( and often know the cause ) that a less experienced pilot wonít even feel. Itís good to have access to someone like that when you arenít sure about something. Even better is someone that can work with the maintenance people to figure out what is wrong.

Another issue you may encounter as someone who only flies one particular aircraft ( not type, but one particular aircraft, like a private owner tends to do ) is that you will just accept that a machine flies a certain way. I had a different client with an R44, and I could tell that there was a rigging issue from the way the machine did hover autos and touchdowns. The owner just accepted it because it was the only aircraft he regularly flew. I worked with the mechanic and we determined that the swashplate was grossly misrigged when it was overhauled ( by someone who didn't know what they were doing, based on all the other problems we found, in this case mounting the swashplate in the wrong location! ). It wasn't really a safety issue in that it wasn't going to come apart or anything, it just couldn't do a hover auto from more than 2 feet, versus the 5-6 feet of a normal R44, let alone do good touchdown autos. If you didn't fly other aircraft of the same type, you might just think that's how R44s did autos...

You should try to emulate the helicopter pilots Harry Reasoner ( the TV reporter ) was describing when he said:

"This is why being a helicopter pilot is so different from being an airplane pilot, and why in generality, airplane pilots are open, clear-eyed, buoyant extroverts, and helicopter pilots are brooding introspective anticipators of trouble. They know if something bad has not happened it is about to."
Paul Cantrell is offline  
Old 13th Jul 2020, 19:12
  #38 (permalink)  
 
Join Date: Nov 2018
Location: San Diego, CA
Posts: 25
Heilcopters vibrate but the pedals do not vibrate at all. The pilot reported feeling vibration in the pedals which is very unusual.
CGameProgrammerr is offline  
Old 13th Jul 2020, 20:55
  #39 (permalink)  
 
Join Date: Aug 2019
Location: USA
Posts: 16
Originally Posted by Paul Cantrell View Post
I

"This is why being a helicopter pilot is so different from being an airplane pilot, and why in generality, airplane pilots are open, clear-eyed, buoyant extroverts, and helicopter pilots are brooding introspective anticipators of trouble. They know if something bad has not happened it is about to."
Like this.
I think I am undergoing that transformation right now
kansarasc is offline  
Old 13th Jul 2020, 22:05
  #40 (permalink)  
 
Join Date: May 2002
Location: Wanaka, NZ
Posts: 2,234
Originally Posted by CGameProgrammerr View Post
Heilcopters vibrate but the pedals do not vibrate at all. The pilot reported feeling vibration in the pedals which is very unusual.
Not correct at all. The pilot reported a tapping in the pedals, not a vibration. Fundamental difference.
gulliBell is online now  

Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service - Do Not Sell My Personal Information -

Copyright © 2018 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.