Keene, NH, USA
C-GNON
De Havilland DHC8
While on descent to the destination airport, an in-flight fire occurred at the right windshield terminal block. The flight crew put on oxygen masks and smoke goggles, extinguished the fire, and landed without incident. The fire damage was concentrated in an area between the upper edge of the terminal block and the lower edge of the windshield gasket where the L2 power wire was routed. The L2 power wire was melted through in this area but remained intact on either side, indicating an arcing failure of the L2 power wire. The damage and melting precluded determination of whether there was any pre-existing damage to the L2 power wire before the incident. Examination of the windshield revealed that it had been installed on the airplane about 5 years before the incident, which was less than the 8.2-year average life reported by the windshield manufacturer. The windshield exhibited minor evidence of moisture ingression into the laminate around the edges and minor erosion of the exterior hump seal that did not contribute to the event. Review of the maintenance records showed that the operator was in compliance with all of the company and airplane manufacturer’s recommended inspections. The operator had performed the mandated inspections required by Airworthiness Directive (AD) but the application of Humiseal to the power terminals had not been completed, therefore, the operator was not in compliance with the AD. The missing Humiseal did not contribute to the event. The most recent inspection, which showed no discrepancies, occurred about 6 weeks prior to the incident.
HISTORY OF FLIGHTOn December 9, 2019, about 1450 Eastern standard time (EST), a Boeing of Canada Ltd., deHavilland Division, DHC-8-301, C-GNON, sustained minor damage when it was involved in an incident near Keene, New Hampshire. The two pilots, one flight attendant, and 15 passengers were not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 129 international passenger flight. In written statements, the flight crew reported that the flight was normal from departure from Montreal-Pierre Elliott Trudeau International Airport (YUL), Montreal, Quebec, Canada to the initial approach into Bradley International Airport (BDL). During decent, about 21,500 feet msl, the first officer smelled smoke and subsequently noticed smoke and fire emanating from the upper forward corner of the right windshield. The crew donned their oxygen masks and smoke goggles and requested priority handling with air traffic control (ATC). The first officer used the extinguisher on the fire and requested vectors to the nearest airport, Keene Dillant-Hopkins Airport (EEN), Keene, New Hampshire. The fire reignited and the first officer used the extinguisher a second time. The captain initially switched both the AC and DC generators off suspecting an electrical fire. The captain then turned the windshield heat switch to the OFF position and re-engaged the AC and DC generators. The crew consulted their charts on the company supplied iPads and found no data for EEN airport. They elected to proceed to BDL since the fire was extinguished and they had already briefed the approach into BDL. After the fire and during the descent, the right windshield cracked. The captain reduced airspeed to 180 knots and maintained a cabin pressure differential of 3 psi. The first officer reported consulting the emergency checklists but could not find anything specific to a windshield fire. The airplane landed at BDL about 1526 EST, was met by airport fire trucks on the runway, and proceeded to the gate after it was determined there was no remaining smoke or fire. AIRCRAFT INFORMATIONThe Bombardier DHC-8-300 had two main windshields that had a laminated glass configuration. The right windshield was installed on November 2, 2014 and had accumulated 10,618.2 hours and 11,762 cycles. The windshields were manufactured using a chemically tempered glass layer, a conductive heating film layer, a urethane interlayer, a vinyl interlayer, a chemically tempered glass layer, a vinyl interlayer, and a chemically tempered glass layer. The windshields were a plug design that used aluminum retainers to secure the windshield in the fuselage opening. A polysulfide moisture seal around the window perimeter protected the interlayer materials from moisture ingression. The anti-ice function performed by the conductive heating film was controlled by the HEAT switch located on the WINDSHIELD panel on the left overhead console in the cockpit. The rotary switch had three positions; OFF, WARM UP, and NORM. The WARM UP position starts the system and applies partial power to preheat the windshield and prevent thermal shock. The NORM position applies full power to the windshields to maintain them at 108ºF ±4ºF. Sensors in the windshield monitor the temperature and the system will turn off power to the windshields if a temperature of 122ºF ±4ºF is reached. In the event of an overheat condition on one of the windshields or a malfunction in the controller or sensors an amber caution light (L WSHLD HOT or R WSHLD HOT) will illuminate on the caution/warning panel. The caution light will extinguish if the HEAT switch is placed in the WARM UP position. The windshield serial number indicated that the windshield was a new unit and was completed on the 365th day of 2013. The Jazz maintenance program had 3 tasks that involved examining the cockpit windshields. A general visual inspection of the windshield moisture seal for cracks, erosion, or wear should be performed every 1600 hours or 365 days and was last performed on October 28, 2019. An internal general visual inspection of the flight compartment above the floor to include the windshields should be performed every 11,000 hours or 3,652 days and was last performed on January 9, 2018. An external general visual inspection of the flight compartment above the floor to include the windshields should be performed every 5,500 hours or 1,826 days and was last performed on January 9, 2018. There were no discrepancies reported from these inspections. Jazz also had Fleet Campaign Directive for a repetitive torque check, witness mark, and application of Humiseal to the windshield electrical connections every 3,000 hours that was last performed on the incident windshield on April 3, 2019. Transport Canada Airworthiness Directive (AD) CF-2017-25 was performed on the incident airplane on January 9, 2018. The average life of the DHC-8-200/-300 windshields manufactured by PPG is about 8.2 years based on limited fleet data provided to PPG. Jazz does not track the life of the windshields in their fleet since they are replaced on condition. AIRPORT INFORMATIONThe Bombardier DHC-8-300 had two main windshields that had a laminated glass configuration. The right windshield was installed on November 2, 2014 and had accumulated 10,618.2 hours and 11,762 cycles. The windshields were manufactured using a chemically tempered glass layer, a conductive heating film layer, a urethane interlayer, a vinyl interlayer, a chemically tempered glass layer, a vinyl interlayer, and a chemically tempered glass layer. The windshields were a plug design that used aluminum retainers to secure the windshield in the fuselage opening. A polysulfide moisture seal around the window perimeter protected the interlayer materials from moisture ingression. The anti-ice function performed by the conductive heating film was controlled by the HEAT switch located on the WINDSHIELD panel on the left overhead console in the cockpit. The rotary switch had three positions; OFF, WARM UP, and NORM. The WARM UP position starts the system and applies partial power to preheat the windshield and prevent thermal shock. The NORM position applies full power to the windshields to maintain them at 108ºF ±4ºF. Sensors in the windshield monitor the temperature and the system will turn off power to the windshields if a temperature of 122ºF ±4ºF is reached. In the event of an overheat condition on one of the windshields or a malfunction in the controller or sensors an amber caution light (L WSHLD HOT or R WSHLD HOT) will illuminate on the caution/warning panel. The caution light will extinguish if the HEAT switch is placed in the WARM UP position. The windshield serial number indicated that the windshield was a new unit and was completed on the 365th day of 2013. The Jazz maintenance program had 3 tasks that involved examining the cockpit windshields. A general visual inspection of the windshield moisture seal for cracks, erosion, or wear should be performed every 1600 hours or 365 days and was last performed on October 28, 2019. An internal general visual inspection of the flight compartment above the floor to include the windshields should be performed every 11,000 hours or 3,652 days and was last performed on January 9, 2018. An external general visual inspection of the flight compartment above the floor to include the windshields should be performed every 5,500 hours or 1,826 days and was last performed on January 9, 2018. There were no discrepancies reported from these inspections. Jazz also had Fleet Campaign Directive for a repetitive torque check, witness mark, and application of Humiseal to the windshield electrical connections every 3,000 hours that was last performed on the incident windshield on April 3, 2019. Transport Canada Airworthiness Directive (AD) CF-2017-25 was performed on the incident airplane on January 9, 2018. The average life of the DHC-8-200/-300 windshields manufactured by PPG is about 8.2 years based on limited fleet data provided to PPG. Jazz does not track the life of the windshields in their fleet since they are replaced on condition. WRECKAGE AND IMPACT INFORMATIONThe right windshield sustained burning and charring damage in the area of the terminal block and the inner glass ply was fractured. There was also some burning and charring damage to the interior airplane trim components adjacent to the forward, upper edge of the windshield. The power and sensor wires to the windshield were cut and the windshield was removed from the airplane. The windshield exhibited a relatively sparse network of fractures on the inboard glass ply. There was minor cloudiness of the interlayer material (evidence of moisture ingression) between the bus bars and the edge of the windshield. There was some minor erosion of the hump seal along the upper and aft edges and no evidence of a hump seal repair. The terminal block remained securely attached to the inboard surface of the inboard glass pane but burning and charring was concentrated at the L2 terminal location. The L2 terminal insert was separated from the block and remained attached to the wire. The screws at the power and sensor connections remained installed with a lock washer between the terminal lug and screw head. Torque striping was evident on all screws except at the L2 location where it was burned away. There was no evidence of Humiseal at the L1 and L2 terminal locations. The screw connections were disassembled, and no signs of cross threading or other discrepancies were noted at any location. All the braid wires except the L2 wire were intact around the edge of the windshield laminate and remained attached to the terminal block. A small section of the L2 wire remained embedded in the charred sealant below the L2 insert location. A small section of the L2 wire was melted away above the upper edge of the terminal block. There was an area of melted glass in the vicinity of the missing L2 wire. The fractures in the inner glass ply emanated from the area of melted glass.
The arcing failure of the windshield heat L2 power wire on the right windshield due to unknown reasons.
Source: NTSB Aviation Accident Database
Aviation Accidents App
In-Depth Access to Aviation Accident Reports
