Ram air turbine, or RAT, deployed on ANA 787-9 JA802A landing in Seattle following a test flight.
SEATTLE – appears confident it will deliver the first to on schedule at the end of June despite having to make a last-minute request to the to approve the aircraft with exemptions for two components that currently do not meet airworthiness regulations.
The appeal, lodged with the FAA on June 4, requests exemptions for the ram air turbine (RAT) and an altitude selector knob on the mode control panel (MCP). Boeing says a capacitor in the RAT is being redesigned to improve reliability and does not currently meet airworthiness standards, having failed during a non-certification-related flight test. But the redesign is not expected to be available for retrofit until February 2015, several months after the 787-9 is due to enter service.
The unit, produced byAerospace Systems, is designed as an emergency source of electrical and hydraulic power and will deploy automatically in flight if both engines fail, or if the pressure drops in all three of the 787’s hydraulic systems. The small propeller-like unit, which is housed in the aft wing-body fairing, will also deploy if all electrical power is lost to the flight instruments or if all four of the aircraft’s electric motor pumps fail and faults in the flight control system develop on approach to landing. The RAT is deployed via a spring-loaded actuator and, once deployed, cannot be stowed in flight. Boeing has applied for an exemption on the basis that the chance of either a dual engine failure or any of the other RAT-deployment scenarios is extremely remote.
The concern over the altitude selector knob follows the discovery that the unit lacks sufficient torque resistance and, when pushed, can be accidentally over-rotated by up to two detents. This means that when this is used in vertical navigation mode, the crew could push it and introduce an error, accidentally flying above or below their assigned altitude. A redesigned MCP is in development but will not be available until May 2015. Boeing has also issued an advisory to the crews of the current 787-8 fleet which is configured with the same MCP.
Although Air New Zealand will be the first operator to take the 787-9, the first carrier to put the stretched aircraft into service is expected to be, which is due to receive its initial aircraft in July. Air New Zealand has yet to operate the 787, while ANA is the world’s most experienced operator of the 787.