曝光台 注意防骗
网曝天猫店富美金盛家居专营店坑蒙拐骗欺诈消费者
avoid that environmental factors could produce the appearance of residual pressure in
the brake system.
1.19. Useful or effective investigation techniques
None.
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Technical report IN-062/2002
2. ANALYSIS
2.1. Operation during the Madrid-Tenerife flight
When the landing gear was lowered during the descent to Tenerife the crew observed
in the WHEEL page of the ECAM that the 24 bars that represent the brakes of the wheels
of the left MLG were lit in amber colour, indicating that there was pressure trapped.
Under those conditions, they did not check the triple indicator located in the central
panel of the cockpit, which would have allow them to note that the pressure was in
the left alternate system, not in the normal system.
Anyway, although the information recovered suggest that the crew did not recognize
the origin and possible effects of the problem and they thought there was a «spurious
indication», they made the right decision of landing with the antiskid connected, which
was correct, and without autobrake, as they were used to do in occasions at the discretion
of the captain.
However, they decided to retard the application of brakes to prevent possible braking
problems in the event there really was a malfunction of the systems, instead of an indication
failure as they suspected. The result of this decision was that during the time the
brake pedals were not pressed, the alternate system was still active and, therefore, the
900 PSI of residual pressure that were present were transmitted to the left wheels, and
the aircraft started deviating towards that side. At the moment of touchdown there
were several pressure releases in the left brakes commanded by the antiskid system
intermittently, and the wheels did not burst.
The copilot, that was the PF during the landing, applied right rudder as coherent with
his intention to delay the brake application, until the deviation was very important, and
the aircraft approached up to 8 m to the left edge of runway 12 and a decrease in the
effectiveness of the rudder was noted as the speed was reducing. At those moments,
he applied heavily right brake and also left pedal, until the aircraft deviated to the right
of the runway axis and came to a stop. The right pedal application started when the
aircraft had between 60 kt and 70 kt of ground speed, and reached its maximum value
when the speed was 50 kt.
At the moment of pedal application, the green or normal system was activated and the
residual pressure of the alternate system fell to 0 psi. However, when the speed was
below 80 kt the pedals had not yet been pressed and there was still a pressure of 900
psi and, when the inhibition of the caution of «brakes residual braking» ended, this caution
was displayed in the ECAM (see paragraph 1.6.4.4).
The result of those circumstances was that the crew was surprised by the behaviour of
the aircraft, and they thought there had been a malfunction in the brake system that
39
Technical report IN-062/2002
remained during the landing roll, and that the brakes heated until the corresponding
ECAM warning was displayed. However, the presence of the antiskid allowed an effective
braking action and avoided the burst of the tires.
Once they had vacated the runway, the crew reset the BSCU. If at those moments they
had checked the triple indicator or the ECAM wheel page, they would have noted that
the residual pressure had disappeared, and therefore that action, required by the Operations
Manual of the operator if the caution appears on ground, was not needed. The
procedures of the manufacturer indicate in one chapter that maintenance action is
required if the caution is noticed at engine start or during taxi, and in other chapter
(«Supplementary techniques» 3.04.32 P1) that the crew may reset the BSCU. That
applies when the aircraft is on ground.
2.2. Maintenance actions in Tenerife Norte
When the aircraft was parked in the apron, the crew commented with the maintenance
personnel the circumstances they had faced during the landing. At those moments,
the immediate problem they had was a high brake temperature, which was cooled with
fans.
From the information gathered it could be concluded that the ground maintenance personnel
was fully aware of the problem of residual pressure that had to be handled
during the previous descent and landing. They actually saw the «Post-Flight Report» provided
by the aircraft that had recorded that the caution «Brakes Residual Braking» had
appeared at 9:12 h in the phase «Cruise 06». This caution was not displayed to the
crew at those moments, because it is inhibited. During the landing roll, below 80 kt,
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