History of the Flight
On 13 December 2016, the aircraft completed routine operations and night-stopped at Manchester Airport. A contracted maintenance organization performed a daily check, including an oil content check of the No 1 engine via the outboard access panel. The check concluded around 2115 hrs, and the Technical Log was signed at 0010 hrs the next day. At 0530 hrs on 14 December, the flight crew began pre-flight checks. At 0550 hrs, the commander conducted a pre-departure inspection in darkness using a torch, finding no issues. Ground crew performed a walkround check with no findings. The aircraft departed from Runway 23R at approximately 0624 hrs and flew uneventfully to Hannover, Germany, landing at 0752 hrs. After parking, ground crew informed cabin crew of a missing panel on the No 1 engine. The flight crew inspected the aircraft. Manchester Airport operations staff recovered the panel from a grass area about 440 m from the runway threshold, along with sections of the hold-open strut from the runway and adjacent areas.
Aircraft Information
The DHC-8-402 (Q400) is a twin-turboprop aircraft. Each engine nacelle has two forward access doors: inboard and outboard. These doors are made of carbon/epoxy composite with foam-filled stiffening ribs, hinged at the top, and secured by four quick-release lock pin latches. The No 1 outboard door and No 2 inboard door provide access for engine oil servicing.
Examination
The recovered panel had all four latches in closed and latched position, with no damage to latch bolts or nacelle receiving fixtures. The aircraft vertical stabiliser had puncture holes on both sides and impact marks on the leading edge de-icing boot. Both VOR/LOC antennas showed impact damage.
Previous Incident on Same Aircraft
On 9 November 2016, the No 1 engine access panel was found missing from G-PRPC after a similar sequence: a daily check at Belfast City Airport, same pre-departure inspection by flight crew and ground crew, and departure from Runway 22. The panel was recovered about 300 m from the runway threshold. Damage was noted to the left wing leading edge de-icing boot and wing skin panel. The latches were all closed with no nacelle damage. Following this, on 29 November 2016, the operator issued Notice to Engineers (NTE) 22 requiring an independent walkround inspection or a delayed double check of panel security, but this was not recorded in maintenance paperwork.
CCTV and Human Factors
CCTV showed the commander's 3-minute pre-departure inspection with torch, including illumination of the No 1 engine access panel area. No CCTV was available of the maintenance check. The contracted maintenance provider's staff at Manchester were unaware of NTE 22, so no additional post-maintenance inspection was performed. The operator's investigation found that the contracted company was not certifying individual tasks or sending hard copies to the operator, contrary to procedures. Engineers involved in both incidents reported a common technique of closing the two upper latches first, then the two lower ones.