Bearskin Metro 3 CYRL accident - Speculation thread

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Ki-ll
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Re: Bearskin Metro 3 CYRL accident - Speculation thread

Post by Ki-ll »

triplese7en wrote: If you did have that triple failure I can pretty much guarantee you will be descending no matter how well you fly the airplane. Basically keep your speed up and do a nice flare before you smack the ground.
That is only if you are able to keep the tube going straight, it must be a challenge....
DonutHole wrote:Its ben awhile but in the 331 what prevents spring pressure from driving the prop to feather when the engine is shut down?
A start lock pin, rotation/inertia keeps it out, when RPM decrease it creeps in and then shear force from feathering spring prevents it from moving out during the consequent start. There are two per propeller I believe.
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BTD
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Re: Bearskin Metro 3 CYRL accident - Speculation thread

Post by BTD »

Ki-ll wrote:
BTD wrote:I have had an engine failure with an nts fail as well. I will say that I am grateful we were very lightly loaded.

In our case it did not prevent feathering.

I have no idea what happened in this case.
Could you please elaborate on specifics? How bad were the forces on the controls (rudder pedals/control column)? What was the airspeed loss? How long did it take you to feather the engine? Was there an associated altitude loss? If you don't mind of course...
I was the F/O and the PNF in the case above, so I don't know the specifics of the control forces. Although significant deflection of rudder and aileron was required to keep it straight. We were IMC but not at night. We had the Gear and Flaps 1/2 out when it occurred. We immediately retracted the gear and flaps to 1/4. As a very lightly loaded aircraft on a short leg, we were just able to maintain level flight with the prop wind milling near 80%. When the failure occurred the yaw was significant enough I almost bounced my head off the window.

We ran the drill and I confirmed 3 times that I had the correct stop and feather. The prop feathered right away and the aircraft flew like a champ thereafter. This was on approach but still a ways back from the field.

This was about 5 years ago, we were a young crew, and I give kudos to the Capt for staying on top of it. He did a great job.

BTD
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Re: Bearskin Metro 3 CYRL accident - Speculation thread

Post by Ki-ll »

BTD wrote:
Ki-ll wrote:
BTD wrote:I have had an engine failure with an nts fail as well. I will say that I am grateful we were very lightly loaded.

In our case it did not prevent feathering.

I have no idea what happened in this case.
Could you please elaborate on specifics? How bad were the forces on the controls (rudder pedals/control column)? What was the airspeed loss? How long did it take you to feather the engine? Was there an associated altitude loss? If you don't mind of course...
I was the F/O and the PNF in the case above, so I don't know the specifics of the control forces. Although significant deflection of rudder and aileron was required to keep it straight. We were IMC but not at night. We had the Gear and Flaps 1/2 out when it occurred. We immediately retracted the gear and flaps to 1/4. As a very lightly loaded aircraft on a short leg, we were just able to maintain level flight with the prop wind milling near 80%. When the failure occurred the yaw was significant enough I almost bounced my head off the window.

We ran the drill and I confirmed 3 times that I had the correct stop and feather. The prop feathered right away and the aircraft flew like a champ thereafter. This was on approach but still a ways back from the field.

This was about 5 years ago, we were a young crew, and I give kudos to the Capt for staying on top of it. He did a great job.

BTD
Thank you very much for sharing this information. I was unable to find any other accounts of crews dealing with NTS failure so far, so this is very valuable.
Did you even figure out what was the reason for the engine packing it in?
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Re: Bearskin Metro 3 CYRL accident - Speculation thread

Post by BTD »

It was an extremely bumpy day and the engine flamed out. If I recall correctly, when the nts system senses negative torque it will turn on the igniters to relight the engine. In our case since the nts system wasn't functioning correctly it didn't switch them on. At the point in the approach and with the high workload we simply feathered the engine. Had the nts worked we might not have even noticed the flame out aside from the igniter light.

Procedures were changed from this and other reasons to run the igniters after the landing checklist and up until the after take off checklist. Apparently the new igniters don't wear out like the old ones so this isn't a concern.

As to why the nts didn't function, I know the answer and it was simple, but i don't feel it is my place to put out that info.

Btd

I am only referring to the situation I was in and I have no idea what the reasons are behind this accident.
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Re: Bearskin Metro 3 CYRL accident - Speculation thread

Post by Iliopolus_1 »

The unofficial word is that the 29 year old male passenger
was a co-joe for Bearskin which would explain why he has not spoken to the media.

Officially there appears to be two stories, one of an approach and the other approaching from descent.

The flight data computer and the data recorder have been recovered with apparently mild amounts of damage
but yet, we have NOT a single announcement of regarding the contents of the voice recorder and data recorder.

Then there is the lack of any information about the final radio calls.

Obviously some one at least knows what went on in this accidental
and coincidentally everyone has gone silent which benefits one one organization.
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Re: Bearskin Metro 3 CYRL accident - Speculation thread

Post by Liquid Charlie »

Nor will you hear anything official until the report is published -- which could be in 18 to 24 months --
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Doc
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Re: Bearskin Metro 3 CYRL accident - Speculation thread

Post by Doc »

Liquid Charlie wrote:Nor will you hear anything official until the report is published -- which could be in 18 to 24 months --
Always wondered why it takes the time it does. Never been involved in an investigation, but the Americans feed information as it comes to pass. Politics. Plain and simple.
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Re: Bearskin Metro 3 CYRL accident - Speculation thread

Post by oldtimer »

To pevent the propeller from going to feather on a NORMAL shutdown, the left seat pilot presses the engine stop button and as the propellor slows from the normal idle of 71% to 50%, the pilot selects full reverse with the power levers and holds them in full reverse until 10%. That should put the props on the start locks. To release the locks, after engine start, the pilot selects either some or even full reverse. This takes the shear loads off the start locks and centrifical force retracts them.
One of the secondary benefits of the NTS test, usually done during taxi, is that it will verify the start locks are released otherwise the props will not change pitch.
If the start locks fail to extend, the prop will go to the feather position but it takes a while. Now that is on the ground without engine rotation to supply oil pressure, I do not know how fast the prop would feather in flight if the engine is simply shut down without being feathered but for the prop to feather on its own, the engine would have to stop rotating otherwise oil pressure will attempt to hold the prop at 100% until the beta tube oil transfer glands are pulled out of the prop pitch control and oil flow to the prop ceases.
Now if it was a gearbox failure, I will not hazard a guess what would happen except I have read where a sudden stoppage twisted the engine in the cowlings and created unacceptical drag.
I am in now way suggesting this is what happened in this accident, rather this is what I have read has or could happen.
I guess we will have to wait for the TSB to conclude their investigation. Meanwhile, lets all fly safely, bow our heads and hold a minute of silence during the funerals.
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Re: Bearskin Metro 3 CYRL accident - Speculation thread

Post by JayVee »

Well said Oldtimer.
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Re: Bearskin Metro 3 CYRL accident - Speculation thread

Post by ODA »

Doc wrote:
Liquid Charlie wrote:Nor will you hear anything official until the report is published -- which could be in 18 to 24 months --
Always wondered why it takes the time it does. Never been involved in an investigation, but the Americans feed information as it comes to pass. Politics. Plain and simple.
The waiting defiantly sucks. I think TSB waits until they have all the info because if only part of the story comes out it can be taken out of context. Either way it would be nice if TSB hired some more investigators to get these reports out a little earlier. Can't fix something that is broken if you don't know it's broken.
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Re: Bearskin Metro 3 CYRL accident - Speculation thread

Post by MUSKEG »

If in fact it is a component failure as speculated might we expect an AD or inspection on mentioned components? They will not wait 2 years to get that ball rolling.
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Re: Bearskin Metro 3 CYRL accident - Speculation thread

Post by Doc »

MUSKEG wrote:If in fact it is a component failure as speculated might we expect an AD or inspection on mentioned components? They will not wait 2 years to get that ball rolling.
Very good point MUSKEG. If it turns out to be a faulty component, we could have it happen again. Two years is a very long time.
Doubt this to be the case however......but, one never knows.
At very least, if there's anything to be learned from the CVR it should be released, at least within the industry, ASAP?
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Re: Bearskin Metro 3 CYRL accident - Speculation thread

Post by cncpc »

The massive plenum failure on the Nav Air MU-2 at Terrace occurred on December 20, 2005.

This piece is copied from the end of the TSB report in this accident. It gives the timeline for action, part of it by Transport Canada, most by the TSB itself.

All in all, I would say that this is a pretty commendable response in terms of letting the industry know where risks may lie. At least in the first responses re the checklist and cracks.
Safety Action Taken

On 06 July 2006, the TSB issued Safety Advisory A060025-1 suggesting that Transport Canada (TC) may wish to remind MU-2B and other twin-engine operators of the importance of ensuring that the required checklist items are completed immediately after recognition that an engine has failed on take-off. (168 days-not unreasonable considering the analysis required)

On 08 September 2006, TC issued Service Difficulty Advisory (SDA) AV-2006-07 regarding Mitsubishi MU-2B cracked combustor plenums (Honeywell TPE-331-6-252M engines). The SDA recommended compliance with the manufacturer's (Honeywell) service bulletin (SB) TPE331-72-2023 to change the combustion chamber from a 3102613-1 (multi-casting boss plenum) to a 3102613-2 (single-casting boss plenum). TC also recommended that maintenance personnel be extra attentive to boss welds when inspecting TPE331 series engines for plenum cracks. (262 days - quite a while considering the evidence was available at the latest when the engine got back to the TSB facility, if not earlier)

On 14 November 2006, the TSB re-issued Safety Advisory A060025-1 suggesting that TC may wish to remind MU-2B and other operators of the effect of flap settings on achieving a required climb gradient following an engine failure in varying ambient conditions. (329 days - depends on how much of a factor this is in this particular accident)

On 18 May 2007, the TSB issued Safety Advisory A06P0298-D2-A2 (Cracks in TPE331 Series Engine Plenum). The advisory described the history of plenum cracking with the TPE331 series engine, particularly in areas where two bosses are in close proximity and a reinforcing weld has been made. Cracks that develop in this area cannot necessarily be detected by visual inspections or even by fluorescent dye-penetrant inspections (FPIs). The advisory suggested that TC may wish to advise commercial operators of the circumstances of this occurrence. Additionally, it suggested that TC may wish to consider the requirement for discussion with the FAA regarding the effectiveness of the maintenance instructions for identifying cracks in the TPE331 series engine plenum. (514 days - I expect this crack analysis was put out to the metal fatigue experts in private industry. It is a fair bit of time though.)

This report concludes the Transportation Safety Board's investigation into this occurrence. Consequently, the Board authorized the release of this report on 13 June 2007.(540 days)
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Re: Bearskin Metro 3 CYRL accident - Speculation thread

Post by cncpc »

One thing which is not mentioned in the Terrace report is that the explosive nature of the plenum failure resulted in considerable distortion of the engine cowling.
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Re: Bearskin Metro 3 CYRL accident - Speculation thread

Post by boeingboy »

OMG.
cnpc - you sure have a hard on for this plenum thing. Yea - they can break.....but in 17 years of working on them - I have never found one cracked, and since they went to the improved design - it's even less likely. However - you make it sound like it's an everyday occurance. And lets face it - The operator at the time was not one of the best around.

BTW - inspections for cracks in the plenum have been incorporated into the maintenance program for the metro for a long time now. They are evey 200 hrs or so - depending on what program you are on.
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Re: Bearskin Metro 3 CYRL accident - Speculation thread

Post by boeingboy »

One thing which is not mentioned in the Terrace report is that the explosive nature of the plenum failure resulted in considerable distortion of the engine cowling.

Two completely different airplanes with radically different cowl designs. A failure on one design may not have any impact on another design.
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Re: Bearskin Metro 3 CYRL accident - Speculation thread

Post by flyinthebug »

boeingboy wrote:OMG.
cnpc - you sure have a hard on for this plenum thing. Yea - they can break.....but in 17 years of working on them - I have never found one cracked, and since they went to the improved design - it's even less likely. However - you make it sound like it's an everyday occurance. And lets face it - The operator at the time was not one of the best around.

BTW - inspections for cracks in the plenum have been incorporated into the maintenance program for the metro for a long time now. They are evey 200 hrs or so - depending on what program you are on.
BIG +1!
cncpc you are starting to sound like PDW with his variable tail wind theories. You know about Plenum failure, we get it. But its one of a possible 50,000 mechanical failures that could have occurred...if it was indeed a complete failure? We still don't even know why they... or even IF they shut down one fan. Speculation is great to learn from, but wild speculation based on your own personal knowledge of one single part of a turbine engine could be quite dangerous. You believe this accident could have been caused by a plenum failure. Ok, we get it. Can we move on to other speculation rather than getting a groundschool style lesson on plenum failure. Much like boeingboy, I have worked with Metros for several years and never once heard of a plenum failure. You`ve made your point, now please drop it. Thanks.
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Re: Bearskin Metro 3 CYRL accident - Speculation thread

Post by pdw »

flyinthebug wrote:cncpc you are starting to sound like PDW with his variable tail wind theories.
Please try to ... a v o i d ... OK ? (but please disregard if only in jest)

It is not correct to suggest the v t w phrase has ever been used in any posts of mine. Yes, i have found that subtle windshears have claimed quite a few lives when it has involved icing on occasion ... and otherwise (usually) only significant shears matter. I wish it could have sunk in just how this works exactly . In the process of reading enough weather related accident reports it's hard not to gain some experience in interpolating for the WX involved.

As for the plenum ... which some seem to think it was ... is different; who knows what exact variation of stresses can result in such a catastrophic failure. To me it's too doubtful to imagine that even a drastic change in the barometer should have much effect on that
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Re: Bearskin Metro 3 CYRL accident - Speculation thread

Post by flyinthebug »

pdw wrote:
flyinthebug wrote:cncpc you are starting to sound like PDW with his variable tail wind theories.
Please try to ... a v o i d ... OK ? (but please disregard if only in jest)
Sorry pdw I was indeed just joking with you. Some of your more recent posts have been well written and thought out. 8)

Carry on.
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Re: Bearskin Metro 3 CYRL accident - Speculation thread

Post by Doc »

Still hard pressed to believe nobody has shared the pilot's transmissions with us. It would say volumes as to their "engine issue"?
The plenum failure theory? Well, they have failed. Pigs have flown, but it's not very common.
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Re: Bearskin Metro 3 CYRL accident - Speculation thread

Post by sky's the limit »

Been away for a while, I see this thread was pulled for some sniping - otherwise a pretty good read. Keep the civil discussion going... it's a good thread minus the stuff I removed.

stl
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Re: Bearskin Metro 3 CYRL accident - Speculation thread

Post by Spinner »

noticed on the end of the CADOR this morning

Date: 2013-11-27
Further Action Required: Yes
O.P.I.: Commercial & Business Aviation
Narrative: UPDATE Aviation Incident Report #13305: Airport maintenance staff observed C-FFZN initiate a missed approach and then commence a left turn descending into the trees. Staff reported downed C-FFZN south of the field in the vicinity of NDB Tower.
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WOW... WHAT A RIDE
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Re: Bearskin Metro 3 CYRL accident - Speculation thread

Post by Ki-ll »

Spinner wrote:noticed on the end of the CADOR this morning

Date: 2013-11-27
Further Action Required: Yes
O.P.I.: Commercial & Business Aviation
Narrative: UPDATE Aviation Incident Report #13305: Airport maintenance staff observed C-FFZN initiate a missed approach and then commence a left turn descending into the trees. Staff reported downed C-FFZN south of the field in the vicinity of NDB Tower.
I wonder if they heard application of power on the good engine (if there was a good engine) and thought it was a missed approach. It was a snowy night after all. I find it hard to believe that they would initiate a missed approach that close to the ground on one engine in a landing configuration.
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Re: Bearskin Metro 3 CYRL accident - Speculation thread

Post by Krimson »

Maybe they were still on two at the time of the missed? We don't know when the failure happened, or if there was one at all.

Engine failure during the missed approach procedure?
Previous engine troubles, maybe fuel bypass occurred during the maneuver resulting in unexpected power loss?
Over-torque during a high workload go around? Result of engine damage?

Just throwing a few ideas out there
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Re: Bearskin Metro 3 CYRL accident - Speculation thread

Post by Maynard »

Very doubtful of a missed approach. As Ki-ll mentioned, the added power after the failure was probably mistaken for a missed approach, given how close they were when the engine had issues.
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