Page 63 - World Airnews Magazine February Edition 2021

NEWS DIGITAL

TRANSPORT CANADA TO

UNGROUND BOEING 737 MAX

event and that they should use all other sources to determine
ransport Canada (TC) has lifted a NOTAM banning Boeing airspeed.
T737 MAX services in the country after an earlier publication Wire routing for the horizontal stabiliser trim system to improve
of an Airworthiness Directive. physical separation of the wiring has to be modified.
The directive details the conditions under which the aircraft is Importantly, Transport Canada has mandated a provision for the
allowed back into Canadian revenue operations. crew to be allowed to disable the stick shaker if it is identified as a
The Canadian regulator’s requirements go beyond those defined nuisance alert.
by the US FAA and Brazil’s National Civil Aviation Agency (ANAC). “During dedicated simulator testing, Transport Canada test
Those two regulators had allowed the MAX back in late 2020 and pilots found that, following the activation of the stick shaker, the
their conditions are similar but not identical to those expected to constant noise and vibration was a significant impediment to the
be published by the European Union Aviation Safety Agency (EASA) safe operation of the aeroplane for the remainder of the flight,” TC
in the coming days. wrote in its directive.
In its directive and in an interim order issued to operators, “The disabling of the stick shaker also improves the crew’s
Transport Canada mandates changes in software, hardware, recognition of the stall warning and disables an incorrect activation
displays, crew alerts, procedures and pilot training. of the elevator feel shift”.
The 737-8 and -9 were banned from operating in Canadian To make turning the stick shaker off easier, TC has mandated the
airspace on March 13, 2019, following two 737-8 accidents within addition of colored caps on the relevant circuit breakers.
less than five months involving aircraft operated by Lion Air and Airworthiness authorities are split as far as how to deal with the
Ethiopian Airlines in which 346 people were killed. stick shaker issue.
Both accidents were linked to the Manoeuvring Characteristics EASA is expected to mandate the same requirements as TC, but
Augmentation System (MCAS) flight control law meant to protect the FAA and ANAC have taken different views.
the aircraft in high angle-of-attack scenarios. Triggered by faulty The FAA’s operations experts within Flight Standards backed
sensor data, MCAS made repeated, forceful nose-down inputs the disabling idea, but their counterparts in Aircraft Certification
which the pilots of both aircraft were unable to recover leading to opposed it, citing the potential of creating more risk by diverting
loss of control. attention from the instruments or flight path, or possibly pulling
In addition to the MCAS software updates designed by Boeing, the wrong breaker.
Transport Canada made several other measures mandatory. The The certification argument won, helped in part by backing from
directive requires implementation of the Boeing Special Attention FAA Administrator Steve Dickson - a former line pilot with 737
SB 737-31-1860 which makes the AOA DISAGREE alert a standard experience.
function. Dickson based his viewpoint in part on his observations when
The alert was also missing from the HGS6000 head-up display he went through a now-required simulator procedure that puts
(HUD). Revised software for the HUD includes display of that alert MAX pilots through an AOA failure that “demonstrates flight deck
that will be implemented in 2021, according to the Canadian effects (i.e., aural, visual, and tactile) associated with the failure,”
regulator. according to new MAX training guidance.
As an interim measure, an operating procedure has been added Among the aural effects is the affected stick-shaker’s constant
to the Transport Canada AFM Appendix informing pilots that the rattling.Q
alert is not available on the HUD during an unreliable airspeed Article courtesy: https://aviationweek.com/

World Airnews | February Extra 2021
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