Living with the 787 QuickFix firebox ?
Alt peker til sannsynligheten at 787-operatörene om ikke lenge blir invitert av Boeing til ä gjenoppta driften, med revampede batterier. Hvordan kommer livet med den säkalte 'QuickFix firebox' til ä se ut for ANA, JAL, NAS og andre 787-kunder ? Noen av spörsmälene som kan stilles vedrörende videre drift har blitt formulert pä engelsk :
The QuickFix firebox won't change anything to the occurrence probability of 'Battery Unserviceable' as an EVENT affecting the Yuasa batteries.
So far, statistics have numbered ca. 150 such EVENTS in approx. 50,000 flight hours. There are two such batteries onboard each 787. Said existing statistical basis was compiled based on a fleet of some 50 aircraft in service. The foregoing sets the scenery for the mathematical assessment of 'mtbf' for the Yuasa batteries, firebox or not.
(S.e.o.o.) 'Battery Unserviceable' is a 'no-go item' : you land with a dead battery, you change the battery ! (fire or no fire). Henceforth, the revamped battery goes together each one with the corresponding containment box. Correct if wrong : to change battery, disconnect cablework and pressure venting hose, remove firebox/battery unit, insert a serviceable firebox/battery unit, connect cablework and venting hose, READY GO !
"S.e.o.o." because otherwise, if the containment box is supposed to remain fixed to the structure (only the battery itself is removed ?) apparently there are 52 (fifty-two !) bolts/nuts to unscrew/refasten to replace the battery unit inside the firebox. Plus disconnect then reconnect cabling/pressure venting hose. This sets the scenery for a 'battery change' as a line maintenance task. How long will this take ? Will the occurrence of a 'battery change' imply the need to perform an unscheduled aircraft change ?
How will these considerations - whereof the appallingly low 'mtbf' - affect the costs of Line Maintenance per flight hour ? How much will this impact upon the Insurance Premium against uncheduled aircraft change imputable to a random 'no-go' item, or otherwise, from Underwriters ? How much will the 'Blind Passenger'-equivalent dead weight of the QuickFix firebox represent in terms of additional fuel consumption ? How much revenue loss will be incurred if/whenever flying at the MTOW structural limit ? How many 'serviceable' Yuasa battery units will the operator need to stock up @ each outstation, to be ready for a need to replace a L-i unit ?; ditto @ the homebase ? What will be the financial cost of owning a stockpile of 'serviceable' batteries ? (remember the unit cost of 1 battery is 14,000 euros, plus the cost of the steel casing ?) What will be the cost of keeping the required dedicated prescincts for storage/insurance/safety monitoring the hazardous L-i materials @ the outstations; @ the homebase ? What will be the annual cost of shipment when/as/to where needed by scheduled (or dedicated AOG) freighter aircraft of the batteries, if the CoMail solution is prohibited by ICAO 'Hazardous Materials' ruling ? Ditto for returning unserviceable battery rotables to Yuasa ? Ditto for disposing of dead L-i batteries ?
The answers to this type of questions will tell us what 'living with the 787 QuickFix firebox' will mean to 787 operators in the near future ... Do not expect Randy Tinseth to provide those answers !
