Canada B763 at Madrid on Feb 3rd 2020, engine shut down in flight, burst tyre on departure

Last Update: December 10, 2021 / 19:34:23 GMT/Zulu time

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Incident Facts

Date of incident
Feb 3, 2020

Classification
Incident

Airline
Air Canada

Flight number
AC-837

Departure
Madrid, Spain

Destination
Toronto, Canada

Aircraft Registration
C-GHOZ

Aircraft Type
Boeing 767-300

ICAO Type Designator
B763

An Air Canada Boeing 767-300, registration C-GHOZ performing flight AC-837 from Madrid,SP (Spain) to Toronto,ON (Canada) with 130 passengers and 8 crew, was departing Madrid's runway 36L when the left hand engine suffered a number of compressor stalls emitting bangs and streaks of flames. The crew shut the engine down, levelled off at 5000 feet initially, later entered a hold at 8000 feet to burn off fuel and had the landing gear inspected by fighter aircraft. The fighter aircraft confirmed one of the left main tyres was blown. The aircraft landed safely on Madrid's runway 32L about 4:10 hours after departure.

The airline already reported the aircraft experienced an engine issue shortly after takeoff, a tyre reportedly ruptured on takeoff. The crew decided to return to Madrid and is currently holding to burn off fuel. The aircraft is designed to operate on one engine. An emergency was declared.

On Feb 5th 2020 the Canadian TSB reported: "During takeoff, rubber from the number 5 main landing gear tire detached. Some debris was found on the runway and others were ingested by the left engine. As a precaution, the flight crew performed an in-flight shut down of the left engine. After burning off fuel to avoid an overweight landing, the aircraft returned to LEMD for an uneventful landing. There were no injuries to the occupants. Preliminary inspection of the aircraft shows damage to the engine and left main landing gear." Spain's CIAIAC opened an investigation.

On Feb 11th 2020 Spain's CIAIAC released first information stating the aircraft was accelerating for takeoff when the tread separated from the aft outboard left main tyre, some fragments of the tread were ingested by the left hand engine. The crew continued and completed takeoff, shut the left engine down and requested to return to Madrid. Due to being overweigt the aircraft remained in flight for several hours to consume the fuel needed to reduce the aircraft's weight to within permissable landing weight. The aircraft subsequently performed a safe landing and stopped on the runway, firefighters cooled the left main gear. The aircraft was then able to taxi to the apron on own power. There was no need to initiate an evacuation, the passengers disembarked normally. There were no injuries. In the post flight inspection damage was found the left engine's air intake, the left engine's blades as well as the left main gear. The CIAIAC is investigating.

On Dec 10th 2021 the CIAIAC released their final report concluding the probable cause of the incident was:

The investigation has determined that the incident involving the C-GHOZ aircraft was caused by the presence of a sharp foreign object (FOD) on runway 36L at Madrid-Adolfo Suárez Airport, which punctured tyre number 5 on its left main landing gear and resulted in the explosion of the tyre and other secondary failures.

The CIAIAC analysed:

The incident involving the C-GHOZ aircraft was caused by the failure of tyre number 5 on its main landing gear at 14:58:03, two seconds before the lift-off at the end of the take-off run. Specifically, the tyre burst and subsequently threw its tread.

Perforation by an external object - FOD

The research carried out on the recovered tyre fragments confirmed, with certainty, that the tyre failed after being punctured by FOD30; in other words, by an external object with the following characteristics:

- The object was a sharp object, which penetrated from the outside in and managed to pierce through the tread and almost the whole of the tyre casing.
- At the moment it punctured the tyre, the object was at an inclined angle.

- It was approximately 1.5 mm wide and 70 mm long.

Breakage sequence

The breakages observed in each of the 9 recovered tyre sections (direct ruptures in section 7 and tapered ruptures in the other sections) made it possible to determine that the failure began in simultaneously, indicates there must have a lot of energy involved. With this energy level in mind, it was possible to rule out a possible low-pressure condition in the tyre at the time of failure.

Furthermore, these types of ruptures are "rapid" ruptures, understood as breakages that occur in less than one turn of the wheel.

Furthermore, the presence of tapered ruptures in the other sections and the increasing distance between the internal and external ply ruptures the further the distance from section 7 indicates there was less energy left in the wheel after a significant part of it had already been released during the initial breakage in section 7. Tapered ruptures are associated with a slower breakage process during more than one turn of the wheel, in which it is possible to observe the process of rupture layer by layer.

Another of the observations confirming the initial point of rupture is the fact that pieces A and B were projected in different directions. Piece A was projected forward and ingested by the engine, but piece B stayed on the runway.

Given that we did not find any discrepancies or discordant elements in the damage caused to the wheel, it was determined that it was sustained during a single event. Based on findings, the failure of tyre number 5 occurred in the following sequence:

the perforation produced by the external object weakened the structure of the tyre and triggered the explosion, the perforation occurred while the tyre was pressurised at its nominal value, the explosion started in section 7, causing all the layers of the tyre to rupture in less than one turn of the wheel, during the rupture of section 7, energy was released instantaneously, the breakages then progressed on either side of section 7 with less energy than the initial explosion, producing tapered ruptures in a process that lasted through several turns of the wheel, finally, and as a consequence of all the above, the tread was thrown.

...

Secondary damages to the tyre failure

The tyre failure in the C-GHOZ event was a fully pressurised explosion phenomenon at the moment when the aircraft had reached its maximum ground speed (end of the take-off run at 176 kt of GS and 168 kt of CAS). As a result, several pieces of the tyre were projected in various directions.

The most problematic issues that affected the remainder of the flight (damage to the left engine and tilt sensor) were produced by the tyre fragments and can therefore be categorised as secondary failures, ruling out prior anomalies in the aircraft.

The most significant of all the secondary failures was the one that affected the engine. Black rubber marks were observed on the lateral engine cowlings, confirming that several pieces of tyre fragment were projected forwards. The high speed of the wheel at the moment the tyre exploded gave the fragments enough energy to reach the engine's suction area and be ingested by it. The surveillance cameras also confirmed that at least one of the ingested fragments was large. The results of the engine inspection confirmed this, finding tyre remains in the first modules and ingestion marks and damage to all the modules. At an operational level, the consequences of this secondary damage were an increase in engine vibrations and N1, which forced the crew to shut it down and continue the flight with just one operative engine.

The second secondary failure to affect the flight of the C-GHOZ aircraft was caused by a tyre fragment that moved up and to the sides, damaging the landing gear tilt sensor. The effect on this system was minor, but sufficient to prevent the crew from being able to retract the landing gear on the initial climb. However, the landing gear sustained no further damage, and the crew subsequently overcame the problem by using the alternative landing gear actuation procedure to operate it.

...

Presence of the object on runway 36L

The origin of the event was the perforation of tyre number 5 by a sharp 1.5 mm wide by 7 cm long object (FOD) on runway 36L at Madrid-Adolfo Suárez Airport.

The review of the operations on Runway 36L showed that 3 aircraft had used the runway since its last inspection. Given that their take-off runs were longer than that of flight ACA837, the three aircraft would also have travelled over the area where the object that affected the ACA837 was lying. This implies that either:

The object was on runway 36L, was not detected in the runway inspection and did not affect the three previous aircraft.

One of the three previously departing aircraft left the object on the runway.

The investigation has not been able to determine which of the two options occurred in the ACA837 incident, and based on the information on FOD compiled in section 1.18, both are considered equally possible.

FOD detection impossibility:

In relation to the capacity to detect an object with these characteristics, the main conclusion of the investigation is that, by using the visual inspection methods currently in force, it is practically impossible to detect them. Therefore, if it was on the runway during the prior inspection, there would have been no guarantees it would have been found and removed.

The review of the runway inspection procedures at Madrid Airport found that the processes, means to be used, and criteria to follow were fully and correctly defined. The personnel who carried out the inspections were also highly experienced, both in their time at the airport and in carrying out the activity. The problem stems from the fact that the inspections are visual and performed by one person, from a moving car that can travel up to 60 km/h and covers areas up to 30 m wide.

While these conditions do not limit the detection of objects with significant dimensions and volumes, they do limit the detection of smaller objects. Despite the fact that the Madrid Airport Runway and Apron Service had detected smaller objects in the past, the general conclusion is that visual inspection methods are not entirely effective because of the limited human capacity to spot them.
Incident Facts

Date of incident
Feb 3, 2020

Classification
Incident

Airline
Air Canada

Flight number
AC-837

Departure
Madrid, Spain

Destination
Toronto, Canada

Aircraft Registration
C-GHOZ

Aircraft Type
Boeing 767-300

ICAO Type Designator
B763

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