@airtren A corollary to the problem of redundancy showed up in BA038. At some stage, and not just in ETOPS, commonality rears its insistent head: eg turbofans burn fuel to produce energy. So then do pitot heads sense air pressure to indicate an absolute value. after 447, it was considered sufficient resolution of the Thales problem to allow one problematic probe to remain installed.
As in 038, the problem was identified in the penultimate position, an oil cooler in the engines. It was not considered ok to change out one TRENT for a GE. It is identical in presentation, a weak link is not allowed to remain in reduindancy, indeed, redundancy is the problem when common fault is the issue. Can we extrapolate? Two pilots are required as crew, and it is impossible to supply identical pilot one for one. In handover, the new pilot is a different solution, by definition, so redundancy in the case of pilots is not an issue, in fact, the "back up" is a fresh resource with different solution making potentials by definition.
The Thales had a specific problem due corrosion at the drain, was this the cause of the icing? from an "anomalous design solution" perspective, the problem becomes the solution, the difference in corrosion support probe to probe makes the Thales probe anomalous, which is the goal in fault prevention in similar systems. Facetiously, but truly, what makes similar devices superior in multiple install is their separate engineering approaches. See 'pilots' above.....
@Linktrained per the report, the AP was ON (selected ON). No?
Last edited by Lyman; 11th Jul 2012 at 16:27.