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Output Number
R20040093
Approval Date
Published Date Time
Recommendation type
Recommendation
Mode
Aviation
Date released
Background Text

Since October 2004, there has been a series of Boeing 737 main
landing gear tyre failures as detailed in Table 1 below.



Of particular concern with the above failures are those associated
with the 737-800 series aircraft.



Those failures involved:



* new generation high gross weight wheel tyres introduced into
service approximately two and a half years ago

* tyres on either the fourth - R4 (one occurrence) or fifth - R5
(five occurrences) retread.



Retreading of aircraft tyres has been a proven practice for many
years, and although failures have occurred from time to time, they
are not a common event, with only four failures involving Boeing
737 aircraft reported to the ATSB during the period between January
2003 and October 2004. As such, the number of occurrences reported
to the ATSB since 13 October 2004 represents a significant increase
in occurrences of this type.



The investigation of these tyre failures is continuing and is yet
to determine the nature and mode of the failures, including any
aspects relating to tyre manufacture, retreading, maintenance and
operational considerations.



Table 1: Summary of Boeing 737 tyre failures since October
2004

Date Aircraft Location Model Summary 13 Oct VH-VOJ Brisbane Qld
737-81Q The aircraft landed with a deflated right inboard main
tyre. The tyre is thought to have deflated during the take-off run
from Perth.

2 Dec VH-VOV Sydney NSW 737-82R During the take-off run from
runway 01, damage occurred to one of the aircraft's main tyres and
tyre tread debris was found on the runway. After landing in Sydney,
the crew noticed that the right landing gear door had been damaged
when the tyre tread separated.

3 Dec VH-VXF Perth WA 737-838 Severely damaged tread found on main
landing gear tyre during post flight maintenance. 4 Dec VH-VOH
Sydney NSW 737-86N While the aircraft was taxiing for departure the
crew heard and felt an unusual bump through the airframe. Shortly
afterwards the Surface Movement Controller advised that the
aircraft appeared to have a deflated main landing gear tyre. After
inspection by ground personnel it was decided to taxi back to the
terminal building, but during this manoeuvre the tyre began to
shred. The aircraft was stopped on the taxiway and the passengers
were disembarked for transport back to the terminal. Engineering
staff replaced the both left main landing gear wheel assemblies and
the aircraft was towed back to the parking area.

15 Dec VH-TJP Perth WA 737-476 The crew reported airframe
vibration after the aircraft took off from Perth and a subsequent
runway inspection revealed rubber detritus in the vicinity of the
rotation point. The crew notified ATC and continued the flight to
Adelaide where the airport emergency services were placed on
standby. The aircraft landed without further incident and the left
main landing gear outer tyre was found damaged and deflated.

19 Dec VH-VOH Canberra ACT 737-86N During the landing, a main
landing gear tyre blew, causing damage to the right landing gear
doors, the right wing flaps and a hydraulic line in the landing
gear bay.



The ATSB investigation is continuing.

20 Dec VH-VOR Sydney NSW 737-8FE After landing at Sydney, ground
engineers noticed sidewall separation and shredding of the tyre
shoulders on the left inboard main landing gear tyre.


Safety Recommendation

In light of the recent industry experience, the Australian
Transport Safety Bureau recommends that Australian operators of
Boeing 737-800 series aircraft review the practice of fitting
retread tyres of R4 (fourth retread) or above, until their
serviceability limitations can be identified.

Organisation Response
Date Received
Organisation
Australian Operators of B737-800 series aircraft
Response Text

On 23 December 2004 Qantas Airways Limited provided the
following response to recommendation R20040093

  1. On 22 December 2004, a visual check of all QANTAS B737-800
    aircraft main gear tyres was commenced. No tyres were reported as
    faulty as a result of that visual inspection for damage.
  2. The inspection will be amended on 23 December 2004 to inspect
    the tyres more carefully on maintenance lay-overs and the pilots
    advised to scrutinise the main gear tyres during their pre flight
    inspections (needed at stations where transits are carried out
    without engineering involvement).
  3. QANTAS maintenance practices on B737-800 aircraft require tyre
    pressure 'top ups' to be annotated in the aircraft Technical Log.
    Tyres requiring frequent 'top up' can be readily identified and
    action taken (progressive tyre deflation and repeated 'top up' is a
    good indicator of incipient tyre failure).
  4. QANTAS require B737-800 tyres to be inflated to 208 psi after
    wheel assembly and left for 12 hours. The allowable pressure drop
    after 12 hours is +/- 5 psi. This practice increases the chance of
    detecting a faulty tyre liner.

On 21 February 2005, Virgin Blue Airlines advised the ATSB that,
'In response to the subject Safety Recommendation, Virgin Blue
Airlines Head of Engineering directed that the maximum retread
level of all B737-800 main wheel tyres used in service would be the
R3 level. This level conforms to the Safety Recommendation.'