EC225 crash near Bergen, Norway April 2016
Join Date: Jun 2016
Location: Aberdeen
Posts: 90
Likes: 0
Received 0 Likes
on
0 Posts
Does anyone know what the actual latest TBO is for the H225 MGB epicyclic module? All I seem to be able to find is that it has been reduced to“ less than half” what it was previously.
[Edit: See correction in post #1616]. At one time (2009) the TBO was 2000FH but under the Maturity Plan had a target of 3000FH.
So, what was previously measured in the thousands is now measured in hundreds.
That is obviously applicable to epicyclic modules fitted, or retrofitted, with the supposedly superior type B planet gear/bearing. I find it slightly odd that, given the possibility of subsurface fatigue cracking, only the TBO is reduced but there is no mention of any revised Service Life Limit? Has this also been reduced and if so, to what?
How exhaustive will overhauls of these gearboxes now be to guarantee them for the next TBO interval? Will each planet gear need to be radiographed or CT scanned for the smallest possible inclusion or micro-defect? Or would they only further examine a gear if it shows signs of spalling, since AH’s faith still appears to hang on that premise?
Who would meet the cost of these enhanced and more frequent inspections and the maintenance time necessary to remove the modules from the aircraft and refit them?
I am also curious as to AH’s ‘confidence’ in the effectiveness of the MCD devices fitted to their MGB system. Mandating inspections of the oil filter and all these MCDs at 10FH intervals seems to suggest that these elusive ‘spalling particles’ can miss MCDs at the epicyclic, at the MGB sump and at the oil cooler (I assume the filter is placed, logically, after the cooler?).
[Edit: See correction in post #1616]. At one time (2009) the TBO was 2000FH but under the Maturity Plan had a target of 3000FH.
So, what was previously measured in the thousands is now measured in hundreds.
That is obviously applicable to epicyclic modules fitted, or retrofitted, with the supposedly superior type B planet gear/bearing. I find it slightly odd that, given the possibility of subsurface fatigue cracking, only the TBO is reduced but there is no mention of any revised Service Life Limit? Has this also been reduced and if so, to what?
How exhaustive will overhauls of these gearboxes now be to guarantee them for the next TBO interval? Will each planet gear need to be radiographed or CT scanned for the smallest possible inclusion or micro-defect? Or would they only further examine a gear if it shows signs of spalling, since AH’s faith still appears to hang on that premise?
Who would meet the cost of these enhanced and more frequent inspections and the maintenance time necessary to remove the modules from the aircraft and refit them?
I am also curious as to AH’s ‘confidence’ in the effectiveness of the MCD devices fitted to their MGB system. Mandating inspections of the oil filter and all these MCDs at 10FH intervals seems to suggest that these elusive ‘spalling particles’ can miss MCDs at the epicyclic, at the MGB sump and at the oil cooler (I assume the filter is placed, logically, after the cooler?).
Last edited by Concentric; 20th Oct 2016 at 17:11. Reason: Confused TBO with SLL.
Join Date: Jan 2009
Location: around and about
Age: 71
Posts: 280
Likes: 0
Received 1 Like
on
1 Post
Spot-on Concentric; a very cogent rationale. I agree totally (and am only an LAE with some limited exposure to TCH design & testing parameters) and they were in USA ~ VFR
Join Date: Jun 2016
Location: Aberdeen
Posts: 90
Likes: 0
Received 0 Likes
on
0 Posts
On re-reading it I now see it actually referred to Service Life, not TBO, so it answers one of my questions. Apologies for any confusion (mine).
So what was, and now is, the Service Life limit?
[Edit: According to previous posts (way back) the SLL used to be 5000 when the TBO was 2000. Without an absolute SLL figure available, we can reason that "less than half" will be <2500, but if the TBO has also been reduced to 1500 as Insider revealed, then for practical purposes since the planet gear cannot be replaced at <2500 without full stripdown of the module it will effectively have to be replaced at each and every TBO, therefore 1500. "Less than half" therefore becomes effectively 0.3, so the life of the component will now be less than one third of what it was. AIBN reported the gearbox on the crashed aircraft had 1340 FH since new, but that of course was with type A planet gears. We do not know how MUCH better the design or manufacture of type B planet gears is by comparison. All these additional inspection measures do not seem to suggest that the difference was all that much.]
Is flying hours the best measure of fatigue loading spectrum on a helicopter gearbox or would some additional parameter like say Torque Hours be more relevant, assuming instrumentation can log this (maybe HUMS already does?).
Last edited by Concentric; 22nd Oct 2016 at 08:29.
I can remember the period in the mid eighties when the logging if flight hours changed . Up to that point flying time for both crew and machine was logged from moving for the purpose of take off to shutting down the rotors. It was then changed to the crew logging it as before but only actual flight time being recorded for the aircraft. Concern was raised that all the running time, which could be quite extended in certain circumstances, was ignored despite concerns that there was a fair amount of stress and wear going on.
These objections were overridden for the obvious financial reasons.
On the fixed wing side engine running time is on the clock and various stages of power are recorded. The wings don't do a lot on the ground so taxiing and suchlike can be ignored. Are we right using the same criteria for helicopters?
These objections were overridden for the obvious financial reasons.
On the fixed wing side engine running time is on the clock and various stages of power are recorded. The wings don't do a lot on the ground so taxiing and suchlike can be ignored. Are we right using the same criteria for helicopters?
Join Date: May 2004
Location: UK
Posts: 57
Likes: 0
Received 0 Likes
on
0 Posts
Fareastdriver: That is a very wise point and I think you really are onto something there.
Geoffers: as ever spot on about TBO and the 'growth of complexity' issues. I very much endorse your idea of swapping your 15 Kg of bumf for 15 Kg of metal in the MRGB!
Geoffers: as ever spot on about TBO and the 'growth of complexity' issues. I very much endorse your idea of swapping your 15 Kg of bumf for 15 Kg of metal in the MRGB!
Fareast, I seem to remember that the Times in the techlog remained start to rotor stop but the MSLS, which they oil companies were billed from, used TO to landing. Could well be wrong as memory isn't what it was.
Last edited by Sevarg; 22nd Oct 2016 at 13:56. Reason: Predictive text and old age.
Rotor start rotor stop
If your rotors are running then your engines are running - does not matter if your wheels are not moving.
EASA is quite clear on what must be recorded.
It matters not a jot what the customer wants recorded - that is for those who fudged the contract to decide.
EASA is quite clear on what must be recorded.
It matters not a jot what the customer wants recorded - that is for those who fudged the contract to decide.
For the TBO times and inspection intervalls it's the actual flight time that what is counts. At least in my job, and all the other flying i did.
EASA/JAR etc. 'flight time' is to regulate the time the crew puts in their logbooks.
EASA/JAR etc. 'flight time' is to regulate the time the crew puts in their logbooks.
Last edited by AAKEE; 24th Oct 2016 at 20:01. Reason: Grammar
Have you actually read a maintenance manual?
I don't know if it has changed but when I was flying offshore the computerised MSLS was filled in with the actual flying times so running time and deck time was not charged to the customer. This information went down to engineering and these times were inserted by the technical computer into the aircraft records. I never filled in tech log times apart from start to stop with two dashed lines in between.
On overseas operations without a computerised MSLS system where the customer was charged for everything the tech log times were taken from the weight on wheels readout of the HUMS.
On a boring day the times could be up to an hour apart.
On overseas operations without a computerised MSLS system where the customer was charged for everything the tech log times were taken from the weight on wheels readout of the HUMS.
On a boring day the times could be up to an hour apart.
Last edited by Fareastdriver; 24th Oct 2016 at 22:36.
Join Date: Aug 2001
Location: Cornwall
Age: 75
Posts: 1,307
Likes: 0
Received 0 Likes
on
0 Posts
In Brazil the customer is charged from first engine start to engines stopped. Regrettably I believe the biggest oil company has returned to the system of allocating a time limit for each flight. This fosters a 'hurry-up' and corner cutting V-NE attitude in the hope that penalties can be avoided.
G.
G.
Now to me the 1 inspection per flight directive suggested that someone somewhere too important to be questioned was not performing a reliability calculation. A calculation with that result is mathematically indefensible. Had they calculated it they would have realised that and recognised the future danger (and not just to crew and passengers, their own personal reputation and career future would be at stake) inherent in such an answer.
So was someone somewhere just, well, guessing? Going on a hunch? Folding to commercial pressures and hoping for the best?
If nothing else I hope we never see such a situation arising ever again.
Join Date: Feb 2009
Location: A nice place
Posts: 160
Likes: 0
Received 0 Likes
on
0 Posts
If your rotors are running then your engines are running - does not matter if your wheels are not moving.
EASA is quite clear on what must be recorded.
It matters not a jot what the customer wants recorded - that is for those who fudged the contract to decide.
Could you provide more details please. As AH would appear to be in contravention of this requirement.
EASA is quite clear on what must be recorded.
It matters not a jot what the customer wants recorded - that is for those who fudged the contract to decide.
Could you provide more details please. As AH would appear to be in contravention of this requirement.
Join Date: Jul 2007
Location: Canada
Posts: 228
Likes: 0
Received 0 Likes
on
0 Posts
Logged time
I recall we did a job one time that involved a 20 minute wait on one leg.
The bean counters decided it was better to just sit at ground idle rather than shut down and start up again.
A argument ensued about component time so we asked Sikorsky.
They said, "Running a 61 at ground idle or flat pitch full RPM generates no significant flight loads", so .... don't log it as component time.
The bean counters decided it was better to just sit at ground idle rather than shut down and start up again.
A argument ensued about component time so we asked Sikorsky.
They said, "Running a 61 at ground idle or flat pitch full RPM generates no significant flight loads", so .... don't log it as component time.
I've never recorded engine operating time in the technical log. Clients get invoiced engine operating time, the boss pays for maintenance based on component (flight) time recorded in the technical log.
Running a 61 at ground idle or flat pitch full RPM generates no significant flight loads
Join Date: Dec 2007
Location: the land of redemption
Age: 53
Posts: 250
Likes: 0
Received 8 Likes
on
1 Post
I remember in CHC Global on AW139 the costumer was charged block time + time with wheels on platform.
Same CHC but in Netherlands, costumer was charged block time only.
Different family I work, different habits I find!
Same CHC but in Netherlands, costumer was charged block time only.
Different family I work, different habits I find!
Oops - comment made as a result of a recent employer's training department trying to tell me that off/on blocks was the time that went in my logbook.
It was not until I queried who do I put as 'Captain' in the incident report if I was sat on the deck in the machine and a bird flew into the rotors...........
It goes without saying that techlog times are different but you might be surprised what is asked not to be recorded.
It was not until I queried who do I put as 'Captain' in the incident report if I was sat on the deck in the machine and a bird flew into the rotors...........
It goes without saying that techlog times are different but you might be surprised what is asked not to be recorded.