DH3 Otter Sept 4, 2022

[Piper_Driver]

An Otter float plane has crashed in Puget Sound north of Seattle with 10 persons aboard. Looks like no survivors. Cause unclear at this time.

Otter crash (https://www.npr.org/2022/09/04/1121089402/plane-crash-puget-sound-washington-state-seattle)

[treadigraph]

https://aviation-safety.net/database/record.php?id=20220904-1

[Diamond Bob]

https://www.seattletimes.com/seattle-news/whidbey-island-floatplane-crash/#update-15356684


https://cimg3.ibsrv.net/gimg/pprune.org-vbulletin/927x994/screenshot_2022_09_05_114619_b000d8f32103db9914ff695f73d47f1 e95f97dd3.jpg

[Diamond Bob]

Plane could have been caught in turbulence or even a microburst that could have directly caused the crash or caused structural breakup. Plane was 55 years old and operated in salt water conditions.

[tdracer]

Search for the missing 9 people officially suspended.

[Maoraigh1]

"An inexperienced seaplane passenger" being concerned about turbulence while "the pilot looked relaxed" and "other passengers were calm" does not indicate severe turbulence.

[Piper_Driver]

Looks like relatives of a Broadway and television actress are among the dead. Condolences to all involved.

Megan Hilty relatives dead (https://www.yahoo.com/entertainment/megan-hiltys-pregnant-sister-brother-172500089.html)

[Liffy 1M]

Though there is no physical evidence yet available, here is one possible scenario, as set out by Dan Gryder. https://www.youtube.com/watch?v=J2MqTGx3Xq4

[TowerDog]

According to Flight Radar the plane came down at almost 8,000 feet per minute, from 1,500 feet that would be about 12 seconds.
IF that is the case something important must have fallen off the Otter.
I flew seaplanes in salt water, didn't like it a bit, quit after 6 months.

[RatherBeFlying]

If I was an Otter operator, I'd be having a very close look at the pitch trim and elevator linkages.

NTSB will likely pull it up to have a close look for missing and broken pieces in the control runs. I don't know about the water depth, but there's considerable tidal currents that will complicate and likely prolong salvage.

[tdracer]

NTSB will likely pull it up to have a close look for missing and broken pieces in the control runs. I don't know about the water depth, but there's considerable tidal currents that will complicate and likely prolong salvage.

Given that witnesses say the aircraft pretty much dove into the water at speed, it may be tricky determining what broke before it hit the water vs. impact damage. Especially after it's been sitting on the bottom of Puget Sound for a while.

[DaveReidUK]

NTSB media briefing today 18:30 PDT.

[tdracer]

It's being reported that the wreckage has been located in ~190 ft. of water. Conditions are rather nasty - 3 to 5 knot current, with poor visibility. At least for the time being they plan to do the recover with remotely operated equipment.

[tdracer]

Recovery underway - reportedly ~80% of the wreckage (and some bodies) recovered.

Bodies, majority of wreckage recovered from Whidbey Island plane crash | The Seattle Times (https://www.seattletimes.com/seattle-news/most-of-whidbey-island-plane-crash-wreckage-recovered/?utm_source=marketingcloud&utm_medium=email&utm_campaign=Evening+Brief+09-29-22_9_29_2022&utm_term=Active%20subscriber)

[RatherBeFlying]

FAA Issues Emergency AD for de Havilland OttersThe airworthiness directive focuses on cracks in the elevator auxiliary spar.

Flying Magazine

[India Four Two]

AD can be downloaded here:

https://drs.faa.gov/browse/excelExternalWindow/DRSDOCID139391948320221005002535.0001%3FmodalOpened%3Dtrue%3 FmodalOpened%3Dtrue

Inspection required within 10 hours or three days.
This Emergency AD was prompted by multiple recent reports of cracks in the left-hand
elevator auxiliary spar
I wonder why inspection of the right-hand elevator is not required.

[megan]

The left elevator has a trim tab that moves dependent on flap selection, connected mechanically to the flaps, normal pitch trim is by means of the usual hand wheel that alters tailplane incidence.

[India Four Two]

An interesting review of Otter loss-of-control accidents:

https://www.aviationlawgroup.com/otters-history-of-sudden-uncontrolled-pitch-movements/

The article states that the elevator tabs are servo tabs.

I've found a copy of the POH online and it confirms Megan's observation that the left "trim" tab is adjusted during flap selection. The POH does not specifically mention that the tabs are servo tabs, except in a "walk-around" illustration.


https://cimg0.ibsrv.net/gimg/pprune.org-vbulletin/1700x374/tailplane_f075ff01294a5c9f1a89da03b8de8a32051427a6.png
https://cimg1.ibsrv.net/gimg/pprune.org-vbulletin/1368x447/wing_flaps_cdfd0d4b94d971d82a35ca980dcd5a370a4ad621.png
https://cimg3.ibsrv.net/gimg/pprune.org-vbulletin/980x868/walk_around_e19193af4c74c97600bdcdf78cc41629119a2624.png


https://www.manualslib.com/manual/1297670/De-Havilland-Dhc-3-Otter.html

[India Four Two]

Well done Aviation Week! :ugh:


https://cimg4.ibsrv.net/gimg/pprune.org-vbulletin/1170x1097/35c24f93_95b4_4024_8963_d2f839a34b49_294134f127b8c9c9bf7b401 b8929185ca973cd22.jpeg


https://aviationweek.com/business-aviation/safety-ops-regulation/faa-issues-emergency-ad-dehavilland-dhc-3-otters

[punkalouver]

Well done Aviation Week! :ugh:

https://aviationweek.com/business-aviation/safety-ops-regulation/faa-issues-emergency-ad-dehavilland-dhc-3-otters

Typical for mainstream media, embarrassing for a magazine like Aviation Week. Based on their publication coverage, I suspect they have new, fashionable hiring practices that lead to this. Not so bad when it is a picture in an airplane magazine, how do you like it for your pilots.

Ask Atlas Air about their Houston 767 crash.

[tdracer]

Typical for mainstream media, embarrassing for a magazine like Aviation Week. Based on their publication coverage, I suspect they have new, fashionable hiring practices that lead to this. Not so bad when it is a picture in an airplane magazine, how do you like it for your pilots.

Ask Atlas Air about their Houston 767 crash.
I just clicked the link, and Av Week appears to have discovered and corrected their error (different picture than shown above).

Maybe the editors take a peak here - some pretty knowledgeable fact checkers on PPRuNe... :ok:

[tdracer]

NTSB has released a preliminary cause for the DHC-3 crash. The horizontal tail actuator had become disconnected - not failed - disconnected. :eek:

They said the separation of this component occurred when a clamp nut that should have been fixed in place by a circular wire lock ring unthreaded and rotated.The NTSB said that while the lock ring was not located in the wreckage, they found that three of five holes drilled in the clamp nut to accept the lock ring were damaged “such that they would not allow for the full insertion of the lock ring.”

“This suggests that it may be possible for a lock ring to be partially installed … not fully seated in a hole in the clamp nut,” the NTSB said. “Further, it might be difficult to visually determine if the lock ring is fully engaged in the clamp nut hole” depending on conditions such as lighting, viewing angle and the presence of dirt or grease.
Whidbey seaplane crash investigators identify possible cause | The Seattle Times (https://www.seattletimes.com/business/boeing-aerospace/whidbey-seaplane-crash-investigators-identify-possible-cause/)

[India Four Two]

https://www.ntsb.gov/news/press-releases/Pages/NR20221024.aspx

I’m currently visiting my daughter in Victoria BC. It’s ironic that I discovered this press release just after I had been down to Harbour Air’s dock to get my floatplane fix.


https://cimg0.ibsrv.net/gimg/pprune.org-vbulletin/1280x960/a60e7223_e4b2_4780_bca5_9f41ea5d267f_333337e4c1d43b29d4e6d9d ad9a5486df3691605.jpeg

[Lake1952]

The NTSB has released 500 pages of its investigation into this accident a year ago...the final report not finished yet.

https://www.king5.com/article/news/local/ntsb-video-deadly-2022-mutiny-bay-floatplane-crash-whidbey-island/281-285fa7fc-d2e8-439a-8cde-46d4a5925234

[tdracer]

Good, fairly in-depth (for a 'civilian' newspaper) article on the suspected cause:
NTSB probe of Whidbey floatplane crash points to likely cause, fix | The Seattle Times (https://www.seattletimes.com/business/boeing-aerospace/ntsb-probe-of-whidbey-floatplane-crash-points-to-likely-cause-fix/?utm_source=marketingcloud&utm_medium=email&utm_campaign=Morning+Brief+9-6-23_9_6_2023&utm_term=Active%20subscriber)

Videos of lab tests conducted by the NTSB released Friday show that the lock ring securing the two parts of the actuator can disengage when the clamp nut at the top is tightened. :uhoh:

Also an interesting 'belt and suspenders" fix being implemented by Friday Harbor Seaplanes in the aftermath.