Originally Posted by Fareastdriver
(Post 10834051)
How else are you going to do it?
The engineers did their best and passed it as fit to fly. The pilot accepted it on the basis that he trusted his engineers. I feel sorry for the bloke that signed it off. No mention of this in the report. Just saying... A pilot who flew the helicopter on 2 July 2020 to Broome Airport reported feeling unusual vibrations through the tail rotor pedals. He described it as if something was repetitively tapping through the pedals. The pilot of the accident flight also conducted a short flight in the helicopter and confirmed the unusual vibrations.
The R44 Pilot’s Operating Handbook (POH) includes the following 'safety tip': A change in the sound or vibration of the helicopter may indicate an impending failure of a critical component. If unusual sound or vibration begins in flight, make a safe landing and have the aircraft thoroughly inspected before flight is resumed. Hover helicopter close to the ground to verify problem is resolved, and then have aircraft reinspected before resuming free flight. The ATSB strongly endorses this advice, and urges any R44 pilot that experiences unusual vibrations through the tail rotor pedals to land as soon as possible and follow the advice in the POH safety tip. |
Originally Posted by gulliBell
(Post 10836400)
Not correct at all. The pilot reported a tapping in the pedals, not a vibration. Fundamental difference.
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Originally Posted by Twist & Shout
(Post 10836418)
A lot of posters are talking about the helicopter being “signed out” or “ok’d” by the engineering staff.
No mention of this in the report. Just saying... Also from the report: We had a 365 which was reported as having a slight kick in yaw on the ground and in the air. Much fault finding of the yaw system ensued with no answer. Two of us after discussing it decided to take a new tack. Kick on the ground, nosewheel castoring bearing had a hard spot. Kick in the air, roll actuator problem. My favourite Aircraft shaking on the ground. Main rotor balancing and structural inspections followed by undercarriage parts replaced. No improvement. Watching the aircraft ground running from a slightly raised location the engineer with me said, " It looks as if it is in negative pitch" We checked the rigging and the blades were about 2 degrees below allowable min pitch. Airtested and pilot returned saying that was much better. Vibration gone? Yes and now you dont have to fly it with the collective under you arm pit. Speechless. |
Vibs
Unusual vibrations can be mysterious and hard to find sometimes..... had a hiller that had a high freq one time when it was on a trailer. Spent a couple of days changing tail rotor system components, and found the freq was caused by the thing being on the trailer.... live and learn.
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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. |
But on the up-side, flying the same aircraft means that you do spot when something changes.
Some years back was once in an R44 with another pilot on climb-out when there was a solid loud metallic "thud" (like someone dropped a bag of tools in the rear footwell). Nothing more, no vibration or loss of power - all smooth. We looked at each other, and agreed immediate return. Engineering inspection followed but couldn't find a fault, told to hover it "heavy" to see if it would repeat. 15 min and no repeat, aircraft released to service but not with me in it. A couple of days later another pilot with commercial passengers onboard experienced the same "thud" in level flight. Made a PAN call and landed, aircraft recovered by road followed by head-scratching in engineering. Someone suggested looking at the Sprag Clutch, which requires disassembly and most shops cannot do. When disassembled it was destroyed internally - fault found. Taught me one thing, if something strange happens and they can't find the fault, then the fault is still there. |
Originally Posted by industry insider
(Post 10834283)
In this case the reported tick vibration wouldn’t indicate an out of balance tail rotor to me. Out of balance is normally much more of a buzz through the pedals.
A simple dynamic balance for the reported problem doesn’t seem like the correct maintenance action. In addition to directly addressing the discrepancy, "Conditional Inspections", in AMM Chapter 5, should be consulted during non routine maintenance. This data includes
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John R81 wrote
But on the up-side, flying the same aircraft means that you do spot when something changes. |
Minor vibration changes can be difficult to pick up for many pilots, including me.
If the change is slow, and over a long period, even more so. It’s “thread drift” here though. Vibes/tapping were reported by one pilot, confirmed by another. An out of balance TR was then eliminated as a source. The RFM call’s for a low hover, followed by a shut down and re-inspection. (Assuming the Vibe was no longer present in the low hover) Rather than the above procedure, the report seems to indicate, that pax were loaded for what was essentially a maintenance test flight. Am I missing something? |
Twist and Shout - I read it the same way as you.:ok:
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Originally Posted by industry insider
(Post 10837431)
John R81 wrote
Not always if the change is gradual. Before the days of HUMS, I visited a base where one crew flew the same aircraft everyday. They were both very professional and were fussy about the state of the aircraft. I performed a line check on one of the crew and thought that the aircraft was a bit rough compared with the last time I had flown it a month prior. A track and balance showed it was close to the limit and had deteriorated, but the crew which flew it every day hadn't noticed. |
That's what happens with prawns when you buy them on the hoof.
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Preliminary report is out. Not conclusive yet.
https://www.atsb.gov.au/publications...r/ao-2020-033/ |
Very concerning though that an aircraft could suffer what seems to be a catastrophic failure immediately after being inspected, and essentially given a clean bill of health - notwithstanding the engineer requiring a test flight - and that the maintenance pilot thought the site unsuitable for a check flight, leaving it for someone else to do even though the site was unsuitable.
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And look at the total hours on the airframe. Glad I don't get into Robbo's
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Originally Posted by catseye
(Post 10877374)
And look at the total hours on the airframe. Glad I don't get into Robbo's
:eek::{:yuk: |
Originally Posted by [email protected]
(Post 10877338)
Very concerning though that an aircraft could suffer what seems to be a catastrophic failure immediately after being inspected, and essentially given a clean bill of health - notwithstanding the engineer requiring a test flight - and that the maintenance pilot thought the site unsuitable for a check flight, leaving it for someone else to do even though the site was unsuitable.
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Originally Posted by Vertical Freedom
(Post 10877434)
Welcome to the sad world of Robinson’s .....just part of the course; bits flinging off & failing on a frighteningly regular basis :ugh:
:eek::{:yuk: VF, your statement is utter rubbish. If we assume that this event was caused by a catastrophic failure of some component (a fair assumption IMHO, although we may all yet find out differently in the end), such events are exceedingly rare in any make/model of helicopter, including Robinsons, and yet by no means unique to any one make/model helicopter, including Robinsons. It is trivially easy to demonstrate this. A 30 second Google search brings up this gem: https://tsb-bst.gc.ca/eng/rapports-r.../a11o0205.html An in-flight main rotor blade separation on a 206. Can you believe it, the venerable 206? Yes, we better stop flying all those, too! And with reference to another, similar incident on a 206 in the same article. Coming at it from the other direction, a search of the NTSB accident database will clearly demonstrate that bits do not fall of Robinson helicopters with any more or less frequency than any other type of helicopter. We've done that study to death on PPRuNe and yet you refuse to accept it because you lost someone close to you in a Robinson accident that you can't explain so you will forever blame the design and the company even though the statistics don't support your position. Meanwhile, while remaining intellectually interested in the root cause of this accident, I don't worry so much because once is happenstance, twice is coincidence, but three times is enemy action, and we have never seen, and are not yet seeing, an epidemic of R44s shedding their tails in dramatic fashion. And if we did see it it would probably happen in one of those countries where they regularly and inappropriately thrash the bejeezus out of their R44s first, thus giving the US aviation community a chance to head off any incipient problems. Of course this is all very idle speculation in the best PPRuNe style. |
[QUOTE=aa777888;10877530]Yes, everyone knows I would be quick to respond to this, so without further ado...
Here we go again..... |
Originally Posted by Vertical Freedom
(Post 10877434)
Welcome to the sad world of Robinson’s .....just part of the course; bits flinging off & failing on a frighteningly regular basis :ugh:
:eek::{:yuk: |
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