Dynamic components after rotor strike
Thread Starter
Joined: Jul 2014
Posts: 446
Likes: 100
From: South East Asia
Dynamic components after rotor strike
Can somebody educate me:
Assume a main rotor gearbox and epicycle (with 300h since New) is involved in a roll over, rotor head and blades are damaged biggly, but gear box looks quite OK.
what hapen to such component:
A: inspection and dynamic testing
B: complete regular 3000h overhaul
C: discarded
if somebody knows how it works please let me know
Thanks
Assume a main rotor gearbox and epicycle (with 300h since New) is involved in a roll over, rotor head and blades are damaged biggly, but gear box looks quite OK.
what hapen to such component:
A: inspection and dynamic testing
B: complete regular 3000h overhaul
C: discarded
if somebody knows how it works please let me know
Thanks
Joined: May 2002
Aviation Qualifications: ATP+Mil
Posts: 18,633
Likes: 1,072
From: Downeast
I'd vote for junking all rotating components right the way back to the Tip of the Tail rotor....and start over after making sure the airframe isn't warped or transmission mounts harmed.
A long chat with the Aircraft Manufacturer and getting their input would be wise as well.
A long chat with the Aircraft Manufacturer and getting their input would be wise as well.
Thread Starter
Joined: Jul 2014
Posts: 446
Likes: 100
From: South East Asia
Well I just put 2 and 2 together: the thread of the TIMO accident and the other thread about EC120 component cost wanting all new components.
that question has been naging my mind:
how much over torque a rotor strike actually is on the MGB?
isn't the inertial shock all from the blades own inertia?
with modern testing method can't we revalidate a part fully?
that question has been naging my mind:
how much over torque a rotor strike actually is on the MGB?
isn't the inertial shock all from the blades own inertia?
with modern testing method can't we revalidate a part fully?
Joined: Dec 2005
Posts: 1,581
Likes: 73
From: England
Well I just put 2 and 2 together: the thread of the TIMO accident and the other thread about EC120 component cost wanting all new components.
that question has been naging my mind:
how much over torque a rotor strike actually is on the MGB?
isn't the inertial shock all from the blades own inertia?
with modern testing method can't we revalidate a part fully?
that question has been naging my mind:
how much over torque a rotor strike actually is on the MGB?
isn't the inertial shock all from the blades own inertia?
with modern testing method can't we revalidate a part fully?
Dont forget the engine is still driving as well unless it had been shut down or failed.
We had a 365 that had a tail strike which lead to the fenestron cutting a slot in the duct.
The main gearbox was found to have a hard spot in rotation and was replaced with the other tail drive components..
What was missed was that the engine manufacturer required the engines to be inspected.
Shortly after return to service the aircraft suffered an engine failure.
This incident would have been classed as a strike not a stoppage.
Joined: Oct 2016
Posts: 168
Likes: 4
From: NW
Well I just put 2 and 2 together: the thread of the TIMO accident and the other thread about EC120 component cost wanting all new components.
that question has been naging my mind:
how much over torque a rotor strike actually is on the MGB?
isn't the inertial shock all from the blades own inertia?
with modern testing method can't we revalidate a part fully?
that question has been naging my mind:
how much over torque a rotor strike actually is on the MGB?
isn't the inertial shock all from the blades own inertia?
with modern testing method can't we revalidate a part fully?
Joined: Sep 2002
Aviation Qualifications: CPL
Posts: 4,721
Likes: 636
From: Great South East, tired and retired
Look at any video where a main rotor hits a cable, or clashes with another rotor, the whole tail boom is shaken off. Huge forces at work, I wouldn't trust any of those components.
Joined: Oct 2006
Aviation Qualifications: A&P
Posts: 1,346
Likes: 270
From: USA
Can somebody educate me:
Assume a main rotor gearbox and epicycle (with 300h since New) is involved in a roll over, rotor head and blades are damaged biggly, but gear box looks quite OK.
what hapen to such component:
A: inspection and dynamic testing
B: complete regular 3000h overhaul
C: discarded
if somebody knows how it works please let me know
Thanks
Assume a main rotor gearbox and epicycle (with 300h since New) is involved in a roll over, rotor head and blades are damaged biggly, but gear box looks quite OK.
what hapen to such component:
A: inspection and dynamic testing
B: complete regular 3000h overhaul
C: discarded
if somebody knows how it works please let me know
Thanks
Joined: Jan 2019
Aviation Qualifications: LAME
Posts: 805
Likes: 642
From: Cumbria
It's an open and shut case; the entire power-train, transmission and rotors are unserviceable until a Certificate of Release to Service is issued by an approved maintenance organisation. That is only going to happen if:
1. The type of occurrence is one that's listed in the Special Inspections in the MM, and inspected/repaired accordingly.
or,
2. The circumstances are referred to the Type Certificate Holder, and specific-to-incident approved data is used to inspect/repair.
1. The type of occurrence is one that's listed in the Special Inspections in the MM, and inspected/repaired accordingly.
or,
2. The circumstances are referred to the Type Certificate Holder, and specific-to-incident approved data is used to inspect/repair.
Joined: Dec 2005
Posts: 1,581
Likes: 73
From: England
It's an open and shut case; the entire power-train, transmission and rotors are unserviceable until a Certificate of Release to Service is issued by an approved maintenance organisation. That is only going to happen if:
1. The type of occurrence is one that's listed in the Special Inspections in the MM, and inspected/repaired accordingly.
or,
2. The circumstances are referred to the Type Certificate Holder, and specific-to-incident approved data is used to inspect/repair.
1. The type of occurrence is one that's listed in the Special Inspections in the MM, and inspected/repaired accordingly.
or,
2. The circumstances are referred to the Type Certificate Holder, and specific-to-incident approved data is used to inspect/repair.
This is the point that the dark arts kick in.
Joined: Oct 2006
Aviation Qualifications: A&P
Posts: 1,346
Likes: 270
From: USA
Well the black art side is finally getting harder depending on your view point. Airbus has seen the light so to speak and now provides a listing of scrapped or destroyed aircraft like other OEMs do. They also provide a means to check serial numbers of items if needed. Have had several checks done but thankfully all was on the up and up with some spare components on the market.
Joined: Oct 2002
Posts: 491
Likes: 3
From: Iceland
Joined: Dec 2005
Posts: 1,581
Likes: 73
From: England
Well the black art side is finally getting harder depending on your view point. Airbus has seen the light so to speak and now provides a listing of scrapped or destroyed aircraft like other OEMs do. They also provide a means to check serial numbers of items if needed. Have had several checks done but thankfully all was on the up and up with some spare components on the market.
They can't provide listings that they do not possess.
Joined: Oct 2006
Aviation Qualifications: A&P
Posts: 1,346
Likes: 270
From: USA
No "linkage" required. The list is update from 3rd party sources. Last I looked the Airbus destroyed/salvage listing had over 5000 aircraft by model and S/N. While its not perfect it does give a benchmark to research from. For example, the Kiwi Xmas tree B2 above is on the list.
Last edited by wrench1; 3rd June 2022 at 15:09. Reason: add example
Joined: Oct 2016
Posts: 168
Likes: 4
From: NW
No "linkage" required. The list is update from 3rd party sources. Last I looked the Airbus destroyed/salvage listing had over 5000 aircraft by model and S/N. While its not perfect it does give a benchmark to research from. For example, the Kiwi Xmas tree B2 above is on the list.
Thread Starter
Joined: Jul 2014
Posts: 446
Likes: 100
From: South East Asia
I do not think it is the role of the OEM to police which airframe should be flying and which airframe should not. (especially when it is in their best intrest to "black list" as many serial number as possible to have the least airframe loose on the market)
why do we have an airworrthiness certificate system then? are we saying it cannot be trusted. if something can be repaired, or inspected according to established procedures, it should get an authorized release form, and if it does it should be authorized by the authority FAA - EASA - CASA - CAA ....
why do we have an airworrthiness certificate system then? are we saying it cannot be trusted. if something can be repaired, or inspected according to established procedures, it should get an authorized release form, and if it does it should be authorized by the authority FAA - EASA - CASA - CAA ....
Joined: Oct 2006
Aviation Qualifications: A&P
Posts: 1,346
Likes: 270
From: USA
why do we have an airworrthiness certificate system then? are we saying it cannot be trusted.
if something can be repaired, or inspected according to established procedures, it should get an authorized release form, and if it does it should be authorized by the authority FAA - EASA - CASA - CAA ....
Joined: Apr 2009
Posts: 12
Likes: 0
From: Australia
I ran a Bell component overhaul shop for a short time. We were often sent components for recertification from third party parts suppliers. We had to be extremely careful with drivetrain components as the Bell sudden stoppage inspection states that if you find any damage as you do the inspection, many components require scrapping, not overhaul.
We had a case where a one 212 fly bar arrived for recertification, the book stated that any damage, both were scrap. I thought it unusual that we asked to only recertify one, not two, this involve a full visual and MPI inspection. We asked were the other bar was, no comment, just send that bar back uncertified.
No idea how many of these types of parts are floating around awaiting recertification.
We had a case where a one 212 fly bar arrived for recertification, the book stated that any damage, both were scrap. I thought it unusual that we asked to only recertify one, not two, this involve a full visual and MPI inspection. We asked were the other bar was, no comment, just send that bar back uncertified.
No idea how many of these types of parts are floating around awaiting recertification.