Created Friday, Mar 3rd 2023 18:05Z, last updated Tuesday, Sep 22nd 2026 16:33Z
A Westjet Encore de Havilland Dash 8-400, registration C-GVEN performing flight WS-3252 from Kamloops,BC to Calgary,AB (Canada) with 74 passengers and 4 crew, was climbing through FL240 out of Kamloops when the right hand engine (PW150) emitted streaks of flame and failed. The crew shut the engine down, descended the aircraft to 10,000 feet and entered a hold for about 30 minutes before safely landing on Kelowna's runway 16 about 45 minutes after stopping the climb.
Kelowna Airport reported the aircraft suffered a mechanical issue with one of the engines, an engine out, and diverted to Kelowna, there was no fire when the aircraft landed.
On Apr 28th 2023 the Canadian TSB reported: "While transitioning from their climb to a cruise altitude of 25 000 feet above sea level (ASL), the crew heard a loud bang. The pilot disengaged the autopilot and the crew saw the No. 2 engine (Pratt & Whitney-Canada PW150A) torque was decreasing with the inter-turbine temperature (ITT) rising above limits. This was shortly followed by a No. 2 engine fire warning. The flight crew declared a MAYDAY emergency with air traffic control (ATC) and actioned the checklist from the quick reference handbook (QRH). The engine was shutdown and secured. The flight crew did not discharge the fire suppressant as there was no indication of fire. The crew requested a diversion to Kelowna (CYLW), BC. ATC cleared the flight CYLW where it landed safely."
On Aug 4th 2023 the TSB changed the classification of the occurrence to accident advising a Class 3 investigation is underway.
On Sep 22nd 2026 the TSB released their final report concluding the probable causes of the accident were:
Findings as to causes and contributing factors
These are the factors that were found to have caused or contributed to the occurrence.
- The No. 2 engine surge was caused by a fracture of a rotor blade in the 2nd stage lowpressure compressor. The rotor blade fractured as a result of a high-cycle fatigue crack, which had initiated from a subsurface location and progressed due to mechanical resonance at 26 000 rpm.
- The engine control system reacted to the loss of engine power by increasing the fuel flow to attempt a power recovery. This added fuel resulted in a fuel-rich mixture that was exhausted into the exhaust duct, resulting in a fire that led to hot exhaust gases being re-ingested into the nacelle.
Findings as to risk
These are the factors in the occurrence that were found to pose a risk to the transportation system. These factors may or may not have been causal or contributing to the occurrence but could pose a risk in the future.
- Operating with the bleed air system set to minimum during climb and cruise on a DHC8-402 aircraft equipped with Pratt & Whitney PW150 series engines may increase the amount of time the engine is rotating in the 26 000 rpm +/−50 rpm range, which likely increases the probability of cracks initiating or propagating in the blades of the current 2nd stage low-pressure compressor design due to mechanical resonance.
Other findings
These findings resolve an issue of controversy, identify a mitigating circumstance, or acknowledge a noteworthy element of the occurrence.
- During the emergency, the flight crew exercised effective crew resource management and adhered to the company’s standard operating procedures and checklists, which resulted in a successful outcome.
The TSB analysed:
Low-pressure compressor 2nd stage rotor failure
An LPC2 rotor blade fractured in flight, which resulted in internal engine damage, a subsequent engine surge, and a loss of power. The flight crew conducted an in-flight engine shutdown and diverted. The investigation determined that a crack had initiated from an unidentified subsurface location on the fractured rotor blade. The highest stress at this location was determined to have occurred because of mechanical resonance at a range of 26 000 rpm +/−50 rpm low-pressure compressor speed (NL) (mechanical resonance mode [M1/5E]).
The engine’s cumulative exposure to 26 000 rpm +/−50 rpm increased after the engine had been restored. This increase was determined to be the result of reduced compressor blade tip clearance. Both this reduced clearance and the exposure to the 26 000 rpm +/−50 rpm range were observed mainly during flights that occurred between November 2022 and March 2023.
As a result, the LPC2 rotor, which had a life limit of 20 000 cycles, experienced a rotor blade fracture at 909 engine cycles since the time at which the LPC rotor had been installed new at the last engine restoration.
Use of the BLEED MIN setting
Flight data trend analysis conducted by the TSB laboratory and Pratt & Whitney Canada identified that the use of the BLEED MIN setting increases the engine operating speed (that is, NL) and that the engine is more likely to run in the 26 000 rpm +/−50 rpm range, especially when ambient temperatures are below −25 °C. WestJet Encore had been utilizing the BLEED MIN valve setting to enhance fuel savings during climb and cruise phases of
flight.
WestJet Encore, once made aware of the flight data trend analysis conducted by staff at the TSB Engineering Laboratory and Pratt & Whitney Canada, revised its operational procedures for the use of the BLEED MIN setting. Following this revision in May 2024, Pratt & Whitney Canada confirmed through its trend data that this rpm reduction brought about by the revised procedures was sufficient to reduce the risk of exposure to operating in the
26 000 rpm +/−50 rpm range.
Engine power loss / exhaust duct fire
Following the LPC2 rotor blade fracture, the engine control system reacted to a loss of engine power and increased the fuel flow in an attempt to recover power. As a result, there was a large quantity of unburned fuel in the exhaust duct, and this rich gas mixture burned in the exhaust duct. For a brief period, some of the hot exhaust gases from the exhaust duct backed up into the aft nacelle through the space between the exhaust duct and shroud. Since 2012, there have been 11 recorded LPC2 rotor blade failures that resulted in in-flight engine shutdown events. Although not all of these events led to an exhaust duct fire, some aircraft (such as the one examined in TSB Air Transportation Safety Investigation A23W0065) experienced significant fire and heat damage, which compromised the integrity of the exhaust duct assembly.
Crew resource management
In a multi-crew aircraft, such as the DHC-8-402, crew members must work with each other, their aircraft, and their environment using associated checklists and company SOPs to effectively manage issues that may be encountered.
In this occurrence, the rotor blade fracture and subsequent rotor failure and engine fire required a diversion, which was successfully handled by the flight crew members because of their prompt action to initiate the Engine Failure / Fire (FLT) / Shutdown checklist. While completing the checklist and setting up the approach for the diversion, the flight crew were contacted by air traffic control. After communicating with air traffic control, the flight crew were able to resume and finish the checklist. During the No. 2 engine shutdown, the captain also enlisted the cabin crew to search for visual signs of fire on the engine and confirm whether any were present.
At times, the captain directed the first officer, who was reading out the checklist, to take the time necessary and not rush through the checklist items. This methodical approach during a time of high workload was effective to successfully manage the emergency and the subsequent diversion.
