more

1
moreWhy We Need to be Proactive

• David F King
• Deputy Chief Inspector of Air Accidents
• Air Accidents Investigation Branch
• United Kingdom
• Measuring Safety Culture
• a Maintenance Human Factors Perspective
• 26th April 2004

2
BAC 1-11
3
BAC 1-11
4
Airbus A320
5
Boeing 737
6
Boeing 737
7
COMMON FEATURES

• Night shift - Circadian lows - Much Maintenance
  at night.
• Supervisors tackling long, hands-on involved
  tasks.
• Interruptions.
• Failure to use the Maintenance Manual - IPC
• Confusing -misleading difficult manuals
• Shift handovers - poor briefing - no detailed
  stage sheets
• Time pressures
• Staff shortages
• Limited preplanning paperwork, equipment, spares
• Determination to cope with all challenges.

8
Boeing 757 Nosewheel Axle failure

• Birmingham to Malaga - uneventful landing.
• Exit via rapid taxiway - 20kts vibration.
• Aircraft stopped - passengers evacuated via
  steps.
• Inspection - right nose wheel canted over -
• Outer Bearing disintegrated.

9
Boeing 757 Nosewheel Axle failure

• 1725hrs Operator informed - Duty Engineer
• Right nosewheel bearing collapsed.
• Telecon Commander
• OK towed slowly - consequential damage? Axle
  change anyway!
• Telecon contract maintenance company
• Two engineers to go to Malaga -
• no can do!

10
Boeing 757 Nosewheel Axle failure

• Another co aircraft due take-off for Tangier
  1800hrs
• Held for divertion malaga with wheels and change
  kit.
• Certifying engineer (LAE) rings in - to check
  shifts!
• Aircraft full of passengers - is he available?
• Feeling tired been Flying microlight - Agrees to
  go.
• 1730hrs Told he is going.
• Duty Engineer copies extracts from AMM
• Torque loading for wheel change
• NOT Time Limits/Maintenance Checks - mandatory
  borescope inspection after bearing failure!

11
Boeing 757 Nosewheel Axle failure

• 1815hrs LAE arrives at Airport
• Asks for mechanic to go with him - Only one seat
  on aircraft!
• 1825hrs Aircraft departs for Malaga
• No opportunity for LAE to check AMM not one on
  aircraft.
• Only authorised procedure for nosewheel axle -
• repair by replacement.
• 1830hrs Duty Eng told aircraft jacked
• Wheel was off axle was not too bad.
• 1900hrs Avionics Eng takes over as Duty Eng.
• 2115hrs LAE arrived in Malaga

12
Boeing 757 Nosewheel Axle failure

• 2115hrs LAE in Malaga - asked about length of
  delay?
• Damaged wheel already loaded - unaccessible.
• Saw bush and axle nut damaged - elected to
  re-use.
• Identified axle damage
• Between bearing lands - 11/2 long 1/16 deep.
• Could see no bluing or overheat on outside of
  axle.
• Decided aircraft OK return Birmingham after
  blending
• Informed Duty Eng at Manchester.
• Duty Eng concerned no repair limits in Manual.
• Contacted Boeing 24 hr desk - go to AMM/provide
  sketch?

13
Boeing 757 Nosewheel Axle failure

• LAE used torch in attempt to see inside axle
• Could not see 7 as Borescope inspection
  required.
• Missed evidence of overheating.
• Blended damage
• Using half round file and emery paper.
• Did not raise ADD but regarded as temporary
  repair
• no drawings or blend limits to work to - no
  blending allowed.
• During inspection distracted
• Tangier aircraft having refuelling problem -
  gave advice.
• During blending distracted
• Refuelling problem again - went to assist.

14
Boeing 757 Nosewheel Axle failure

• LAE replaced right wheel without problem
• Changed left hand wheel.
• 2215hrs (1 hour after arrival Malaga)
• Contacted Duty Eng
• brief description of damage
• Aircraft satisfactory for service
• Axle change should be planned when schedule
  allowed.
• 2259hrs Aircraft Took off.
• 0121hrs Aircraft landed at Birmingham
• Slowed to 12kt when axle failed.

15
Discolouration 400C
Region dressed since mechanical damage - before
fracture.
16
Fracture initiation in dressed region
17
COMMON FEATURES

• Night shift - Circadian lows - Much Maintenance
  at night.
• Supervisors tackling long, hands-on involved
  tasks.
• Interruptions.
• Failure to use the Maintenance Manual - IPC
• Confusing -misleading difficult manuals
• Shift handovers - poor briefing - no detailed
  stage sheets
• Time pressures
• Staff shortages
• Limited preplanning paperwork, equipment, spares
• Determination to cope with all challenges.

18
Thats All Folks
19
WINDSCREEN CHANGE

• Short staffing - Night shift of 7 down by 2.
• Shift Manager does job himself, alone.
• A/C remote - took Manager away from his other
  duties.
• Time pressures - AM shift short - aircraft to be
  washed.
• Task between 0300-0500 hrs - time of Circadian
  lows.
• Manager was on his 1st night work for 5 weeks.
• MM only used to confirm Job straight forward.
• IPC was not used - IPC was misleading.
• The safety raiser used provided poor access.

20
WINDSCREEN CHANGE - SHIFT MANAGER

• assumed bolts fitted OK - incorrect bolts 4 years
  before.
• chose bolts by matching - stores below min stock
  level.
• ignored advice of storeman on bolt size.
• bolts from open AGS Carousel - faded labels -
  dark corner.
• did not use his reading glasses at any time.
• increased torque from 15 lb in to 20 lb in.
• didnt notice excessive countersink or next
  window different.
• didnt recognise different torque for corner
  fairing.
• rationalised use of different bolts next night
  doing same job

21
FLAP CHANGE

• LAE and team were new to the task.
• LAE authorised but A320 rarely seen - 3rd party
  work.
• Planning was a job card - 'change flap' some
  tooling.
• Maintenance Manual in AMTOSS format.
• Tooling deficient or incorrect - no collars for
  spoilers.
• LAE requested experienced help - none available.
• Other tasks during delays - changes in tasking.
• Task worked in early hours - time of Circadian
  lows.
• Tried task without disabling spoilers - couldn't
  do.
• Spoilers disabled no collars/flags - deviation
  from MM.

22
FLAP CHANGE

• Shift hand over verbal, paperwork incomplete -
  misunderstanding over spoilers.
• Spoilers were pushed down during flap rigging.
• Familiarity with Boeing aircraft where spoilers
  auto reset.
• Flaps functioned - spoilers not - a deviation
  from the MM.
• Duplicates were lead by day shift engineer.
• Failure to follow Maintenance Manual.
• During flight crew Walk round nothing amiss.
• Pre-flight check, 3 seconds mismatch
  control/surface position required to generate
  warning.
• Engineers demonstrated a willingness to work
  around problems without reference to design
  authority - including deviations from Maintenance
  Manual.

23
BORESCOPE INSPECTION

• Inspections not in accordance with Task Cards or
  MM-
• HP rotor drive covers not refitted.
• Ground idle engine tests not
  conducted.
• Tech Log wrongly signed
  completed as in MM
• Work originally planned for Line, transferred to
  base.
• Line and Base staff shortages - three Base
  supervisors.
• Minimal preplanned paperwork - Line Maintenance.
• To keep authorisation Base Controller did
  inspections.
• A/C remote - took Controller away from other
  duties.

24
BORESCOPE INSPECTION

• Line Engineer gave verbal handover to Base
  Controller.
• Inadequate reference to Maintenance Manual.
• Use of an unapproved reference source - school
  notes.
• Poor lighting.
• Many interruptions.
• Early hours of morning - Circadian lows.
• 9 previous occurrences.
• Borescope Inspections routinely non procedural.
• Quality Assurance system had not identified
  deviations.
• Regulators monitoring had not corrected lapses.

25

• Although many ingredients are demonstrated to
  have come together to create these incidents,
  what if some are there all the time?

Fatal Accidents
1
The Heinrich Ratio
Accidents
10
Reportable Incidents
30
Incidents
600
Tye/Pearson Bird