A report by the UAE GCAA shows maintenance errors led to an engine hot gas leak incident on a DHC-8-300 in 2012.
On September 9, 2012, a DHC-8-315Q aircraft, registration A6-ADB, operated by Abu Dhabi Aviation, departed from Abu Dhabi International Airport (OMAA) at 06:45 LT on a scheduled 35-minute passenger flight, to Das Island Airport (OMAS) with 49 persons on-board. After several minutes in flight, and before reaching 5,000 feet, a passenger informed the cabin crew member about signs of paint blisters on the right hand engine inboard panel, as seen through the cabin window.
The passenger’s observation was confirmed by the co-pilot who informed the captain of a possible engine fire. A PAN was declared and Abu Dhabi air traffic control (ATC) gave an immediate clearance for landing. Cockpit indications were normal but the crew decided to return to the airport due to the possibility of an engine fire. Unknown to the crew and passengers, the same condition also existed on the left hand engine.
The aircraft landed uneventfully and the airport fire service confirmed that there was no sign of fire. No injury was reported among the passengers or crew members.
The Air Accident Investigation Sector determines that the cause, of this incident, which resulted in an ‘in-flight turn back’, was due to the omission to reinstall the left engine igniters on both of the aircraft’s engines following maintenance work. The maintenance error occurred as result of a number of contributing factors.
The Contributing factors to the event were:
(a) Unrecorded maintenance work performed on the Aircraft by the Operator’s maintenance personnel.
(b) Introduction of an engine wash without a maintenance task card.
(c) Engineer signed off work on the aircraft without verifying that the work had been performed.
(d) Mechanics performed unsupervised work.
(e) Mechanics performed engine motoring without the Operator’s approval.
(f) Work was performed on the aircraft without maintenance task card.
(g) Engine washes were not considered a critical task by the Operator.
(h) Performing similar tasks on both engines during the same maintenance visit.
(i) Not carrying out an engine run after the engine washes were performed
(j) Not performing a system check of the engine ignition system after engine wash normalization.
(k) Not attaching a telltale streamer to indicate that parts have been removed and are in a concealed area.
(l) Operator’s quality oversight, as unrecorded work was being performed regularly prior to the Incident.
(m) Mechanics not signing for work performed, following engine washes.
(n) The removal, in 2009, of the engine wash card which was requiring a signature by the mechanic, before the engineer signoff.
(o) The effect of fatigue on the decision making process of the Engineer due to his shift pattern of working an average of 8.5 hours a day for 32 days with 2 staggered days off.
(p) The Engineer, in addition to supervising the shift work, was required to enter data into the Operator’s electronic system.
(q) Application of the Operator’s human factors training, as unrecorded work was a practice associated with engine washes.
(r) The Operator’s SMS implementation, since there were GCAA audit findings between 2009 and 2012.
(s) Lack of guidance provided by the GCAA, and the Operator, of the effect of shift duty times, and management of the risk associated with fatigue.
- GCAA Report (PDF)