[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...

[pininja]

In this case, the author goes on to say the manufacturer had the same recommendation for both cables. Airlines that knew of the issue didn’t communicate with the manufacturer, and Air Moorea hadn’t identified the problem with the relatively new aircraft added to their fleet. The damage in the cable wasn’t visible in their regular inspections.