To add to the good stuff that Magnersdrinker is trying to explain, I think one subtlety that was lost in the quotes above are the fact that the XV230 BoI's comments were related to the insulation of the hot air system's ducts, and not the ducts themselves. The few sentences before the bit quoted above were:
The Board believes that a lack of guidance on the allowable condition for hot air pipe insulation contributed to its gradual deterioration in some areas and that gaps between different types of insulation provided points of weakness in the system, making it possible for fuel to touch bare pipe metal at operating temperatures in excess of 400C. Thus, the Board was of the opinion that the hot air system's maintenance policy was a Contributory Factor in the loss of XV230.
So, they're not suggesting that there was a problem with ducts rupturing to allow hot air leaks there -- their point is that problems with insulation around the healthy, intact pipes could allow fuel to touch bare pipe metal. This is different from the quote about XV227:
a. A maintenance policy is investigated for the ruptured duct and all similar ducts.
since that is talking about problems with the ducts themselves rupturing and allowing hot air leaks.
Had the accidents happened the other way round and both BoIs commented on the maintenance of the hot air system, there would have been a link since a hot air leak would also be an ignition source that could start a fire if fuel had leaked nearby. But they didn't and, as with Magners, I therefore can't relate the recent comment about insulation allowing the intact bare pipes to be an ignition source with the older comment about the pipes failing, and allowing hot air to leak.