Porter DH8D near Fredericton on Mar 10th 2018, sparks, burning odour followed by multiple system faults

Last Update: October 19, 2018 / 15:17:16 GMT/Zulu time

Bookmark this article
Incident Facts

Date of incident
Mar 10, 2018

Classification
Incident

Airline
Porter Airlines

Flight number
PD-1480

Departure
Halifax, Canada

Destination
Montreal, Canada

Aircraft Registration
C-GLQG

Aircraft Type
De Havilland Dash 8 (400)

ICAO Type Designator
DH8D

A Porter Airlines de Havilland Dash 8-400, registration C-GLQG performing flight PD-1480 from Halifax,NS to Montreal,QC (Canada) with 72 passengers and 4 crew, was enroute at FL240 about 45nm southwest of Fredericton,NB (Canada) when passengers reported a burning odour and sparks from the left hand cabin wall near the overhead bin above seat 14A. Cabin crew alerted the pilots and began to examine the area, the flight crew initiated the smoke drill, donned their oxygen masks, declared emergency reporting an electrical fire on board and diverted the aircraft to Fredericton. Cabin crew noticed the odour was dissipating and they could not find any trace of fire. In the meantime the flight crew received caution messages concerning the left hand AC power (which further triggered cautions for TRU, windshield heat control, stick pusher and #1 pitot heat), other caution lights flickered momentarily. On approach to Fredericton the crew observed an IAS mismatch, autopilot disconnect and yaw damper fail caution indications consistent with a blocked pitot tube. The aircraft landed safely on Fredericton's runway 09 with emergency services on stand by. The crew shut the aircraft down and initiated a rapid disembarkation onto the runway. The passengers were bussed to the terminal.

The runway was NOTAMed closed for about 5.5 hours.

The Canadian TSB reported the source of sparks and smoke was determined to be arcing of the 115V 3 phase AC supply feeder in the left wing root to fuselage connector plug assembly. The 50A circuit breaker in the left hand nacelle junction box was found tripped. The components were retained by the TSB for further investigation.

On Oct 19th 2018 the TSB released their final report releasing following key safety message:

The incorrect assembly of some AC power feeder connectors has caused stressed wire terminations, a known issue in the Q400 series aircraft fleet. The stressed wire terminations have resulted in heat damage and, in some cases, significant electrical arcing.

The current carrying capacity of connector 9811-J711 is 46 A. However, because the 50 A circuit breaker protecting the circuit is rated at a value exceeding the connector’s rating and is of the thermal type, an overcurrent condition could be experienced for a substantial amount of time before the breaker finally trips.

In this occurrence, the cause of the electrical short circuit was not identified. Although electrical arcing damage consistent with previous occurrences was found, the wiring alignment was correct and the bend radius of the wiring was within manufacturer specifications, suggesting that these conditions alone may not be the sole source of the electrical faults and heat damage in the AC power feeder connectors.

Service Letter DH8-400-SL-24-016 advises air operators to carry out inspections to detect play in the pin-locking mechanism and identify conditions that may cause stress in the wires of the AC power feeder connectors. However, the actions published in the service letter have not been made mandatory by an airworthiness directive; it is not known how many air operators have completed the recommended actions specified in the service letter or what conditions have been identified. As a result, the manufacturer may not have the information required to take further action to address this issue.

The TSB described the damage:

The 50 A thermal-type circuit breaker in the left engine nacelle AC control box was found to have tripped. The source of the smoke and heat damage was determined to be arcing from the 9811-J711 electrical connector plug assembly in the fuselage at the left-wing-root area. The arcing damage of the electrical connector is consistent with an electrical short circuit within the connector. Because of the destructive nature of this arcing, the connector pin–locking mechanisms and insulation insert material were obliterated, and the source of the electrical short could not be identified.

The electrical arcing that occurred before the 50 A thermal-type circuit breaker tripped caused minor pitting damage to adjacent wiring bundles, and heat damage and sooting to the insulation blankets and the structure of the outer panel of the overhead baggage compartment(Figure 2 and Figure 3).

The TSB Engineering Laboratory performed a computerized tomography (CT) scan of the occurrence electrical connector, then generated 3-dimensional models of the connector superimposed on wiring to represent the manufacturer-specified minimum and the maximum wiring bend radius between the pin-locking mechanisms and the strain relief clamp. The 3-dimensional models were compared to occurrence images, and it was determined that the wiring alignment was correct and that the actual bend radius of the wiring was within manufacturer specifications.

The TSB reported that two other cases associated with AC power feeder connectors had been reported to them in 2016, in addition Bombardier had been informed about 8 other cases. As result Bombardier had released service letter DH8-400-SL-24-016, the TSB annotated:

In October 2016, Bombardier issued Service Letter DH8-400-SL-24-016 to inform Q400 operators of the 2 occurrences associated with AC power feeder connectors that had occurred earlier that year. The service letter explains that incorrectly assembled connectors may result in stress on the connector pin-locking mechanism and that, over time, vibration acting on the locking mechanism may cause fractures and result in an electrical short. It also notes that in 1 case, wires were incorrectly aligned between the strain relief clamp and the wire termination. The service letter advises operators to carry out inspections of specific AC power feeder connectors, including connector 9811-J711, at the next maintenance opportunity. The inspections are intended to detect play in the pin-locking mechanism and to correct conditions where wires became stressed in the assembly process, such as the application of incorrect bend radius or incorrect wiring alignment. The service letter provides specific examples of these conditions, and offers solutions to correct the conditions.

According to Transport Canada, the performance of actions published in service letters (or similar technical publications) by manufacturers is optional unless the actions are made mandatory by an airworthiness directive.
Aircraft Registration Data
Registration mark
C-GLQG
Country of Registration
Canada
Date of Registration
Mjmfdgnnl jqhjqmb Subscribe to unlock
Certification Basis
FkfkqmhAjAmhhfibmiAgpkibcegdbcejneAfqAiljAjf Subscribe to unlock
TCDS Ident. No.
Cnfp Subscribe to unlock
Manufacturer
Dehavilland
Aircraft Model / Type
DHC-8-402
ICAO Aircraft Type
DH8D
Year of Manufacture
Eglm Subscribe to unlock
Serial Number
Jeec Subscribe to unlock
Aircraft Address / Mode S Code (HEX)
Qijmqd Subscribe to unlock
Maximum Take off Mass (MTOM) [kg]
Phpqb Subscribe to unlock
Engine Count
F Subscribe to unlock
Engine Type
AAehenkkpn Subscribe to unlock
Main Owner
CbhpjndpepgnmclpcfbhmmkdlqlqlfAmnjkdbdehpjfkgnqki ippiqhnqeAqnqbqlgpbhcijihmp jppkeppkcce Subscribe to unlock

Aircraft registration data reproduced and distributed with the permission of the Government of Canada.

Incident Facts

Date of incident
Mar 10, 2018

Classification
Incident

Airline
Porter Airlines

Flight number
PD-1480

Departure
Halifax, Canada

Destination
Montreal, Canada

Aircraft Registration
C-GLQG

Aircraft Type
De Havilland Dash 8 (400)

ICAO Type Designator
DH8D

This article is published under license from Avherald.com. © of text by Avherald.com.
Article source

You can read 2 more free articles without a subscription.

Subscribe now and continue reading without any limits!

Subscribe now
Are you a subscriber? Login
Subscribe

Read unlimited articles and receive our daily update briefing. Gain better insights into what is happening in commercial aviation safety.

Compare our plans

Send tip

Support AeroInside by sending a small tip amount.

Send tip

Related articles

Newest articles

Subscribe today

Are you researching aviation incidents? Get access to AeroInside Insights, unlimited read access and receive the daily newsletter.

Pick your plan and subscribe

Partner

Blockaviation logo

A new way to document and demonstrate airworthiness compliance and aircraft value. Find out more.

ELITE Logo

ELITE Simulation Solutions is a leading global provider of Flight Simulation Training Devices, IFR training software as well as flight controls and related services. Find out more.

Blue Altitude Logo

Your regulation partner, specialists in aviation safety and compliance; providing training, auditing, and consultancy services. Find out more.

AeroInside Blog
Popular aircraft
Airbus A320
Boeing 737-800
Boeing 737-800 MAX
Popular airlines
American Airlines
United
Delta
Air Canada
Lufthansa
British Airways