Flydubai B738 at Dubai on Aug 8th 2017, hydraulic failure caused by damaged tyre

Last Update: September 20, 2018 / 18:54:37 GMT/Zulu time

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Incident Facts

Date of incident
Aug 8, 2017

Classification
Report

Airline
Flydubai

Flight number
FZ-81

Destination
Bahrain, Bahrain

Aircraft Registration
A6-FDS

Aircraft Type
Boeing 737-800

ICAO Type Designator
B738

A Flydubai Boeing 737-800, registration A6-FDS performing flight FZ-81 from Dubai (United Arab Emirates) to Bahrain (Bahrain) with 29 passengers and 6 crew, departed Dubai's runway 12R and was climbing through 250 feet AGL when the crew received indication of the loss of pressure of the hydraulic system A. The crew continued the climb to 4000 feet and entered a hold to work the related checklists. The aircraft subsequently positioned for an approach to Dubai's runway 12L, landed safely, vacated the runway via taxiway N8 and taxied to the apron.

A postflight inspection revealed the #1 tyre (outboard left main tyre) tread center rib completely peeled off the tyre, the tyre had remained inflated however.

The United Arab Emirates Civil Aviation Authority (GCAA) released their final report concluding the probable cause of the incident was:

The Air Accident Investigation Sector determines that the cause of the Incident was the rotation of the damaged No. 1 tire inside the left main wheel well that consequently caused damage to some components and lines of hydraulic system A, and the subsequent hydraulic system A pressure loss.

Contributing Factors to the Incident

The Air Accident Investigation Sector identifies the contributing factors to the Incident as follows:

- The intermittent operation of the left alternate antiskid valve, which most probably allowed the two wheels of the left main landing gear to enter the wheel well while still spinning.

- The rotating wheel peeled portion of the center tire tread rib of the number 1 wheel did not operate the frangible fitting, resulted in a continuation of the left gear retraction, allowing the number 1 tire peeled portion to damage the hydraulic system A and other parts located in the vicinity.

The GCAA analysed that the tyre became damaged during takeoff, however, remained inflated until after the aircraft arrived at the stand after landing back. The damaged tread pieces could not be found after landing back, it was probable the tread pieces were lost when the landing gear was extended. A trace of a cut was identified however. The GCAA analysed:

The trace of a cut with tear-lines on the top belt ply that extended out of the cut was possibly caused by a foreign object debris (FOD) or rough ground surface. However, the Investigation could not determine where, when and how the cut damage had occurred. There was no evidence that any FOD was present on the runway during the take-off, nor on other aircraft takeoff and landing, prior to or after the take-off of the Incident Aircraft. However, it is possible that the cut occurred on a previous flight and, was not detected on the inspections prior to the Incident.

Premature signs of tire internal components separations, such as bulges, localized rubber splits, or uneven wear, may be a sign of delamination damage. In that case, it is important to remove tires from service when any evidence of separation is observed before a flight. During ground roll and high-speed rotation, even small areas of tread separation may grow into partial or full tread rubber loss. However, there was no evidence that the No. 1 tire had internal components separations prior to the flight.

The tire had been re-treaded twice prior to the Incident. It had been installed on the Aircraft 13 days after the second re-treading that was carried out by the tire manufacturer according to the manufacturer’s specifications. The tire had been in service for 66 cycles prior to the Incident.

Although the Investigation could not determine the cause of the tire damage, the Investigation believes that the Operator should include re-treaded tires in its reliability program, and to ensure that on-wing monitoring of nose and main wheel tire pressures is sufficiently robust to ensure TSO specifications for re-tread tire integrity are maintained throughout the tire operational spectrum. The reliability program should also consider the operational and environmental conditions.

The GCAA analysed: "Both flight crewmembers operated the flight in accordance with the Operator’s standard operating procedures (SOP). They carried out all necessary checklists, including the non-normal checklist for loss of hydraulic system A."
Incident Facts

Date of incident
Aug 8, 2017

Classification
Report

Airline
Flydubai

Flight number
FZ-81

Destination
Bahrain, Bahrain

Aircraft Registration
A6-FDS

Aircraft Type
Boeing 737-800

ICAO Type Designator
B738

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