
The Crash of Air Moorea Flight 1121: Analysis - troydavis
https://medium.com/@admiralcloudberg/the-crash-of-air-moorea-flight-1121-analysis-4cbc6ea283d3
======
nessunodoro
I'm a big fan of Cloudberg. His writing style is consistent, clinical,
thorough, objective, and contextual. I highly recommend his analysis/timeline
of the 2018 Camp Fire.

------
paulsutter
These are actually very durable great planes, often found on island routes
with short runways like St Barth’s

Well written analysis of the failure

~~~
tonyarkles
I live close to an airport that has a lot of commuter/short-haul routes. The
Dash 8 is popular. Once you look at the Twin Otter and the Dash 8 side-by-
side, you can't ever unsee the similarities! Now I just see these giant Twin
Otters coming through every day!

[https://en.wikipedia.org/wiki/De_Havilland_Canada_DHC-6_Twin...](https://en.wikipedia.org/wiki/De_Havilland_Canada_DHC-6_Twin_Otter)

[https://en.wikipedia.org/wiki/De_Havilland_Canada_Dash_8](https://en.wikipedia.org/wiki/De_Havilland_Canada_Dash_8)

------
redis_mlc
The comments pointlessly feteshize this accident investigation, but Air Moorea
(and Chalk's Airlines) were both really the result of carrying passengers in
worn-out airplanes.

Besides control cables, corrosion, fatigue, worn seat tracks and unavailable
parts are also issues in these dinosaurs.

[https://en.wikipedia.org/wiki/Chalk%27s_International_Airlin...](https://en.wikipedia.org/wiki/Chalk%27s_International_Airlines)

------
Firerouge
> In France, small aircraft like the Twin Otter were not required to have
> cockpit voice recorders, but Air Moorea had installed one anyway. This
> proved invaluable to investigators, so for the sake of future
> investigations, they recommended that all planes with capacity for 9 or more
> passengers be equipped with a CVR.

But earlier the author stated that the pilot

> uttered an expletive, the only word recorded on the cockpit voice recorder

So it doesn't quite follow how this crash caused the new regulations

~~~
jobigoud
Stringing together the two quotes, it would appear that the expletive, the
only word recorded on the cockpit voice recorder, proved invaluable to
investigators.

~~~
Firerouge
Perhaps it is that simple, but it doesn't make sense to me how that expletive
could have been so vital.

I can only think that it helped investigators formulate the timeline of
exactly when things broke. However, that doesn't seem vital to the
investigation, or something that couldn't have been determined with basic
flight data recording.

------
ssambros
"Air Moorea didn’t know it had both types in its fleet, it replaced all its
control cables on the interval specified for carbon steel cables — about once
a year."

Did they just ordered the replacement parts per catalog without looking at
what exactly is being installed? I mean, they would have noticed that one
plane has a different part number.

~~~
stordoff
If I'm reading the report correctly, it's not clear they ever replaced the
cables. The plane was new to the fleet (and was the only plane with stainless
steel cables), and "Air Moorea specified on the parts follow-up documentation
that the life of the rudder and elevator cables was limited to one year
(operations in saline atmosphere) from 2 October 2006" (the cables had been
checked and re-installed prior to handover). The accident occured 9 August
2007.

Furthermore, even if they had known, it's not clear it would have made a
difference:

> Twin Otter cables can be made of carbon steel or stainless steel. These two
> types of cables are interchangeable on the airplane. Their inspection and
> replacement programmes are the same although their behaviour is different:
> carbon steel cables are more sensitive to corrosion, stainless steel to
> wear.

> The checks required by the manufacturer are based on the number of flying
> hours performed or on the calendar and not on a number of cycles. This
> inspection rhythm is well adapted for the phenomenon of corrosion but not
> for that of wear.

Absent their own experience with the cables ("Several operators had adopted
special inspection intervals closer together than those mandated by the
manufacturer"), would they have changed anything?

[https://www.bea.aero/docspa/2007/f-qi070809.en/pdf/f-qi07080...](https://www.bea.aero/docspa/2007/f-qi070809.en/pdf/f-qi070809.en.pdf)

------
DuskStar
For more by Admiral Cloudberg, he has a subreddit:
[https://old.reddit.com/r/AdmiralCloudberg/](https://old.reddit.com/r/AdmiralCloudberg/)

