On 14th December 2018, a Boeing 737-300, 5N-BUO with flight number APK7100 was operated as a scheduled passenger flight from Murtala Muhammed International Airport, Lagos to Akanu Ibiam International Airport, Enugu on Instrument Flight Rules (IFR) Flight Plan. The service was initially intended to be operated by another Boeing 737 with nationality and registration marks 5N-BUK in the operator’s fleet, but due to Engine cowl valve light illumination and the unserviceable wing Flap system, the aircraft was changed.
Thereafter, passengers were relocated to another aircraft (5N-BUO) for the flight.
While performing the Pre-flight inspection on 5N-BUO, the Captain noticed the pressurization mode controller was in the alternate position and the left engine bleed switch on the air conditioning control panel was placarded ‘INOP’. The Captain said he invited the Engineer into the cockpit who verbally explained that the No.1 engine supplies bleed at 18 psi and that it was working regardless of the placard placed on it.
