Hi there. A KLM flight I was on from Amsterdam to the US was delayed by 6 hours due to technical issues, resulting in a missed connection and having to spend the night at a hotel near the airport and taking the next flight early next morning. All in all a ~12h delay to my final destination.

I wrote a complaint to KLM claiming €600 compensation according to EU rules. However, KLM just wrote me back (after 4 weeks) saying that the delay was not in their control so I'm not entitled to the compensation. Here's what they wrote:

We can confirm that your flight was delayed due to a technical problem to the auxiliary power relay /../ However, we regret to inform you that having studied the details and circumstances of your claim, you are not eligible for EU compensation in this instance, as no predefined compensation is stipulated under the European legislation currently in force for cases of flight delay there were beyond the airline control, such as in your case an unexpected aircraft technical failure.

Is this true? Isn't technical failure completely under their control? I'm sure it was unexpected for them, but if they had maintained their auxiliary power relay a bit better, it would not have failed in the first place. If this is not under airline control, then what is??

They said that in spite of not being eligible for anything, they'd still send me a €200 travel voucher valid for one year on KLM flights. Unfortunately, this is not very useful for me since I don't plan to fly with KLM within the next year.