Composite Skin In-Flight Fire Risk Analysis
amicus,
I understand that you did your best in trying to convince the FAA etc. to require thermal insulation throughout the inner surface of the 787 fuselage.
To the extent that I understand the logic of FAA rulemaking, they refer to quantitative estimates of risk. For example, how many aircraft expected to be lost per 10,000,000 flight hours, or some such measure. Their reasoning seems to be, that risks below a certain level don't require regulatory intervention (no doubt I'm oversimplifying, but this is the crux).
To your knowledge, did anyone conduct such an analysis, and present risk estimates to the FAA? If so, is any part of that publicly accessible?
As I tried to outline a couple of days ago, fires are Awfully Dangerous to transport planes at altitude, REGARDLESS of material. So the threshold question would be, how much greater is the quantified risk with composite vs. aluminium fuselage skins.
Further, we might attempt to classify in-flight fires inside the fuselage into three levels of severity:
III. Combination of intensity and duration (under reasonable assumptions of crew response) sufficiently small, that the plane is likely to continue to a safe landing, regardless of construction, or top-half insulation of composites.
II. Intermediate-level, in which fire performance (including inflammibility) of skin material is expected to make a difference to the likelihood of saving the plane, and in which top-half insulation of composite skins could also make a difference.
I. Sufficiently great intensity and duration that the plane would be lost, whether of aluminium or composite skin construction, even with top-half insulation of composites.
Fires falling into levels I and III don't make any difference to flight risk -- none whatsoever.
Did anyone analyze the risks associated the level II fires? For example, did anyone attempt to quantify the parameters of fires that are survivable for aluminium skinned aircraft, but non-survivable for composite skinned (with and without top-half insulation)? Did they then look at aviation safety records, to estimate their rate (for example, how many apparent level II fires have occurred in the last 250,000,000 jet airline departures?
If no such analysis was made, that perhaps doomed the efforts to argue the point with the FAA.
Of course, this London fire offers an opportunity to revisit the question. It can only help the case, to support it with a quantitative risk analysis.