DHC-3T Lost in WA Puget Sound

[geodoc]

Operated by NW Seaplane, not Kenmore Air. Looks like a GE / Walter engine'd machine. Very high rate of decent before impact per FlightRadar24. Bummer.

https://www.flyingmag.com/1-dead-9-miss ... MzMzOTAyS0

https://twitter.com/flightradar24/statu ... 20220904-1



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[Antique Pilot]

Operated by NW Seaplane, not Kenmore Air. Looks like a GE / Walter engine'd machine. Very high rate of decent before impact per FlightRadar24. Bummer.

https://www.flyingmag.com/1-dead-9-miss ... MzMzOTAyS0

https://twitter.com/flightradar24/statu ... 20220904-1



This Otter was serial # 466 the last one built. It’s former Canadian registration was VQD. It was operated at various times out of Red Lake, Lac Dubonnet, Whitehorse , and Prince Rupert.

AP

[onceacop]

Link will probably be pulled shortly. Sobering and sad. https://m.youtube.com/watch?v=J2MqTGx3Xq4/

[FishermanIvan]

Dan Gryder is a fucking idiot, but it's hard to disagree with him.

There's a reason why Canadian Otters have two linkages on the trim tab.

[geodoc]

Dan Gryder is a fucking idiot, but it's hard to disagree with him.

There's a reason why Canadian Otters have two linkages on the trim tab.

Reading a bit about the AD that applies. It appears that the initial AD was released that required an additional push / pull rod on the servo tab (not the flap system connected tab) applicable to the Vazar (PT6), Garrett, GE / Walter and PZL recip STC'd aircraft. Later it appears that that requirement was dropped on the Garrett and GE / Walter STC'd aircraft. At least this is what it seems from what I can glean from a perusal of internet available info. Is there an AME or other person knowledgeable about this AD and its history that an chime in with the straight skinny?

https://www.federalregister.gov/documen ... -airplanes

Of course this may all be a pig in a poke since at the moment they have yet to even locate any wreckage let alone look over any of it. Truth is it will be months before it gets beyond unsupported speculation.

Any yes, Dan Gryder is , how should I put it ................. a ____________ ______________?


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[rigpiggy]

As a former cdn aircraft, I would think it would already have complied with the ad prior to export.?

[geodoc]

As a former cdn aircraft, I would think it would already have complied with the ad prior to export.?

It would probably depend on whether the Walther STC / installation was accomplished before or after it was exported to the US. Also whether it was installed in either Canada or the US whether the version of the AD was current that rescinded the requirement for incorporating the 2nd servo tab push pull rod on Walter engine STC's. At least that's the way I read it.


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[oldncold]

Otter has been found, komo news seatlle reported today that a reasearch underwater rov that was undergoing testing was requested by ntsb to help in search for the missing otter. They assisted and found the otter no further info yet and only 1 person body has been recovered

[T-bag]

I was flying a DeHaviland product that same day within 20nm of N725TH’s flight path only 30 minutes before the incident. We had delayed our flight for an hour due to wx (low vis). The vis around 1:30 was 4 sm in mist. But worse along route to Vancouver. Port Angele was similar. I’m not convinced it was mechanical but I’ve never flown the Walter version. But I do agree with the feelings about Dan Gryder. What a Wanker.

Looks like AD 2004-05-01 only applied to the Lurton install (P&W). Probably because there was more of them operating and TC and the FAA had more info on them. Also I heard the Texas turbine has a different thrust line angle resulting in less to no buffeting on the tail. Plus the prop spins slower having a lesser impact on the tail. As you can see. Not every Turbine Otter is the same. I’m no expert but with over 10,000 hours in Single Otters on floats I reckon it’s a solid aircraft. Well at least the ones we fly.

[T-bag]

I was flying a DeHaviland product that same day within 20nm of N725TH’s flight path only 30 minutes before the incident. We had delayed our flight for an hour due to wx (low vis). The vis around 1:30 was 4 sm in mist. But worse along route to Vancouver. Port Angele was similar. I’m not convinced it was mechanical but I’ve never flown the Walter version. But I do agree with the feelings about Dan Gryder. What a Wanker.

Looks like AD 2004-05-01 only applied to the Lurton install (P&W). Probably because there was more of them operating and TC and the FAA had more info on them. Also I heard the Texas turbine has a different thrust line angle resulting in less to no buffeting on the tail. Plus the prop spins slower having a lesser impact on the tail. As you can see. Not every Turbine Otter is the same. I’m no expert but with over 10,000 hours in Single Otters on floats I reckon it’s a solid aircraft. Well at least the ones we fly.

[fish4life]

I was flying a DeHaviland product that same day within 20nm of N725TH’s flight path only 30 minutes before the incident. We had delayed our flight for an hour due to wx (low vis). The vis around 1:30 was 4 sm in mist. But worse along route to Vancouver. Port Angele was similar. I’m not convinced it was mechanical but I’ve never flown the Walter version. But I do agree with the feelings about Dan Gryder. What a Wanker.

Looks like AD 2004-05-01 only applied to the Lurton install (P&W). Probably because there was more of them operating and TC and the FAA had more info on them. Also I heard the Texas turbine has a different thrust line angle resulting in less to no buffeting on the tail. Plus the prop spins slower having a lesser impact on the tail. As you can see. Not every Turbine Otter is the same. I’m no expert but with over 10,000 hours in Single Otters on floats I reckon it’s a solid aircraft. Well at least the ones we fly.

There is lots of solid aircraft out there but fatigue is fatigue and these are old airframes that are getting pushed harder than every with the power of the engines. The blue water crash in Manitoba where the wing folded up is another example.
DeHavilland built and incredible product but I don’t think the designers ever imagined it would still be flying in 2022 with turbine engines bolted to the front.

[phillyfan]

How is the Bluewater accident related to Turbine Engine modification?

[oldncold]

CNN reporting 6 more bodies recovered from wreckage. Also NTSB have recovered 80 percent of wreckage including the engine. They have identified the 5 of the bodies ,but are still looking to identify the 6th. There also was a body recovered several miles away from the crash a week ago
Investigators are working to verify if they were in the crash

[W5]

https://www.avweb.com/aviation-news/eme ... tor-spars/

Emergency AD Issued For Otter Elevator Spars

The FAA has issued an emergency AD mandating the immediate inspection of the left-hand elevator auxiliary spar on De Havilland DHC-3 Otters a month after an Otter floatplane crashed in Washington State, killing all 10 people onboard. The AD was issued Oct. 4 after “multiple recent
reports of cracks” in the spar, the FAA said. “The unsafe condition, if not addressed, could result in elevator flutter leading to elevator failure, with consequent loss of control of the airplane,” the AD says. Although there’s no suggestion in the AD that it was prompted by the accident, witnesses reported the aircraft suddenly dove into the water in Mutiny Bay, just off Whidbey Island, last Sept. 4.

The emergency AD requires “repetitive detailed visual inspections of the entire left-hand elevator auxiliary spar for cracks, corrosion, and previous repairs, and depending on the findings, replacement of the left-hand elevator auxiliary spar. This AD also requires sending the inspection results to the FAA.” The type certificate for the Otter is held by Canadian manufacturer Viking Air and Transport Canada, which has been consulted about the AD.

[boeingboy]

Yea - except that this was spurred from the FAA dragging their feet for years....they issued this not from evidence in the crash but from a routine inspection done on another Otter and unrelated to the crash.

TC has made the aging aircraft inspections an AD since 2018 which would cover all this....the FAA only proposed making it an AD in Feb 2022. They are also now going to make the lift strut insp mandatory. Again - already done here a while ago.

Seems like the FAA is way behind the 8 ball lately.

I might also add that it very well could be something else - including a medical issue as the NTSB has said absolutely nothing as of yet.

[geodoc]

Juan with an update:





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[J31]

https://www.youtube.com/watch?v=mfFy4Sjb5sY

[W5]

NTSB Identifies Potential Safety Issue In Fatal DHC-3 Crash


https://www.avweb.com/flight-safety/acc ... c-3-crash/


The National Transportation Safety Board (NTSB) announced on Monday that it has identified a possible safety issue with the flight controls of a De Havilland Canada DHC-3 Turbine Otter that crashed into Mutiny Bay, Washington, last month. According to investigators, the horizontal stabilizer actuator was “found separated where the clamp nut threads into the barrel section” with further examination suggesting that the “components separated by unthreading as opposed to being pulled apart in tension.” The circular wire lock ring used to prevent the pieces from unthreading has not been found in the wreckage.

“At this time, the NTSB does not know whether the lock ring was installed before the airplane impacted the water or why the lock ring was not present during the airplane examination,” the Board said in its investigative update. “The NTSB, in coordination with the Transportation Safety Board of Canada, has asked that the manufacturer draft instructions for an inspection of the actuator to ensure that the lock ring is in place and properly engaged to prevent unthreading of the clamp nut. Those instructions will be released and provided to all operators of the DHC-3 airplane worldwide in a Service Letter.”

The aircraft went down on Sept. 4, 2022, killing the pilot and all nine passengers onboard. The NTSB noted that approximately 85 percent of the airplane was recovered from the sea floor. The investigation is expected to continue with examinations of both elevators, interviews of the FAA principal operations and maintenance inspectors assigned to the operator, a review of maintenance records and interviews with maintenance personnel. The Board is also planning to conduct an evaluation of lock ring failure modes and lock ring installation instructions along with an aircraft performance study. As previously reported by AVweb, the FAA issued an emergency AD requiring immediate inspection of the left-hand elevator auxiliary spar on DHC-3 Otters on Oct. 4 due to the crash.

[CpnCrunch]

Some more info here:

https://www.ainonline.com/aviation-news ... r-accident

[karmutzen]

Maybe an engineer can explain the findings to me. It wasn't corrosion, it wasn't maintenance inspection frequency, it wasn't the elevator spar. It was a the safety ring snap that locks a locknut, allowing the threaded barrel to back out until the elevator control disconnected.That component would have been looked at during maintenance on April 21.

To the aerodynamicists out there, is the elevator on the DHC-3 different than other aircraft? ...... This aircraft was trimmed in level flight, why didn't it stay that way?

Got an explanation this morning...
"Otter tailplane is a completely different design than a turbo beaver. Otter has a trimming stabilizer with a jackscrew attached below the leading edge and 2 hinge points below the trailing edge. It’s R/H elevator has a servotab where you would expect a trim tab and the L/H elevator has a “flap compensating tab” similarly located.

Turbo beaver, and recip beaver, has a jackscrew mounted below the stabilizer trailing edge which drives a bellcrank assembly and 2 trim rods which actuate 2 traditional style trim tabs.

If the jackscrew on a beaver becomes jammed you’re stuck with unfavorable trim forces, it can’t really come apart like the jackscrew in the accident otter did.

If the jackscrew on an otter suddenly loses its top then the stabilizer is free to violently bang between its two extremes of travel. At this point the pilot is, at best, faced with pitch control reversal but is most certainly totally fucked."

[phillyfan]

So. The way this part works. Is it safe to assume the ring was in but came off at some point shortly before the accident? Would it have then spun off with a few turns of the wheel?

[howey]

Here is the a release from the NTSB. Note the recommendations to TC and the FAA.

https://www.ntsb.gov/investigations/Acc ... IR2208.pdf

To Transport Canada:
Require all operators of De Havilland Canada DHC-3 airplanes to
conduct an immediate one-time inspection of the horizontal stabilizer
actuator lock ring in accordance with the instructions in Viking Air
Limited Service Letter DHC3-SL-27-001 and report their findings to
Transport Canada. (A-22-24) (Urgent)