Pakistan International Airlines Flight 688


Pakistan International Airlines Flight 688 was operated by Pakistan's flag carrier Pakistan International Airlines as a domestic passenger flight from Multan to Lahore and Islamabad. At 12:05 pm on 10 July 2006, the Fokker F27 deployed on the route crashed into a field when one of its two engines failed shortly after takeoff from Multan International Airport. All 41 passengers and four crewmembers on board were killed. It was the deadliest plane crash in Pakistan until 2010 when an Airbus A321 flew into Margalla Hills in Islamabad while on approach to Benazir Bhutto International Airport.
The final report of Pakistan's Civil Aviation Authority revealed that one of the Fokker F27's 48-year-old engines developed a problem shortly after take-off and, due to engine mismanagement by the pilots, the crash ensued.

Course of accident

As the plane accelerated on Runway 36, its starboard engine began to spool down. The pilots elected not to abort take-off and continued the take-off roll. Airborne, the plane veered to the right while flying at low altitude. The plane stalled, clipped trees, hit an electric power line and impacted the ground in an inverted attitude in a wheat field. It exploded and burst into flames. The plane lost contact with Multan International Airport control tower two minutes after takeoff. Everyone on board died instantly. It was reported that the post-impact fire was so intense that no-one on board could have survived.

Aircraft

The aircraft was a Fokker F-27 registered as AP-BAL. The aircraft was manufactured in February 1964 and had a total flying hours of 73,591. The engines, produced by Rolls Royce, were manufactured in 1958. The Inspection Form from Engine Log Book containing all relevant run-up data was despatched to Rolls Royce, Germany. It was determined that all the parameters were in required range.

Passengers and Crew

The victims included Vice-Chancellor of Bahauddin Zakariya University, Prof. Dr. Mohammad Naseer Khan. Two flight attendants and three doctors, were also among those killed. One of the flight attendants was pulled out alive, but later died.
The Captain was 53-year-old Captain Hamid Qureshi. He has a total flying experience of 9,320 hours and joined Pakistan International Airlines in December 1989. The First Officer was 28-year-old First Officer Abrar Chughtai with a total flying experience of 520 hours, of which 303 were on the Fokker F-27.

Investigation

A special investigation team was assembled by PIA that announced they would compile a report about the crash within a week of the accident. At the same time, the Air League of PIA Employees Union has charged the PIA administration with responsibility for the crash. They argue that the airline operated flights with too few crew members, promoted incompetent officials, and carried out substandard overhaul work on aircraft, among other flaws.
Following this incident, all PIA Fokker aircraft were withdrawn from service and replaced with ATR aircraft. Mr. Muhammad Umer Draz Awan, the district manager of Faisalabad immediately visited the site and took control of the area until the managing director of PIA reached the site.
The investigation commission reported that following the accident a runway inspection revealed metal debris on the right side of the runway, between 4000 and 6800 feet down the runway, which was identified to originate from turbine blades of the right hand engine. The tracks on the ground suggested the aircraft veered to the right about 4000 feet down the runway and subsequently paralleled the runway centre line to the right of it.
The investigation highlighted that although the aircraft had been certified as airworthy, the "procedure for issue of certificate of airworthiness is inadequate and weak to ensure that aircraft is maintained in accordance with Technical Literature", effectively putting into doubt that the aircraft was airworthy. The investigation added, that the last review of the aircraft for renewing certificate of airworthiness was done by an engineer with avionics background only. The investigation commission added pressure stating: "It is the opinion of the inquiry committee that present procedure of C of A cannot ensure that aircraft is maintained in accordance with Technical Literature and there is no Service Bulletin or Mandatory Airworthiness Directive outstanding. The inspection by Airworthiness for renewal of C of A is also a weak area." The investigation highlighted that for example the right engine's feathering motor was found in a poor condition of maintenance with wrongly fitted bearing and worn out armature, PIA's engineering did not possess diagrams of the CVR and DFDR for maintenance, the engine oil condition had not been monitored by any Spectrometric Oil Analysis Program and the oil was extremely dirty.
A tear down examination of the right hand engine revealed that the "thrust bearing of right engine was improperly assembled during last overhaul at DART Engine Shop PIAC in September 2005." The thrust bearing assembly had been turning eccentric while being assembled and thus was orbiting instead of an ideal rotation. The resulting imbalance caused reverse bending loads on the bolt heads of the bearing assembly resulting in the failure of one bolt head, which created even more stresses and caused the bearing housing to open after the next 5 bolts had failed. The rotor assembly of the turbine increased its radii of orbit and caused the turbine rotor to free itself and move forward resulting in the turbine discs and blades to experience heavy rubbing, the turbine blades failed due to resulting thermal stresses and broke away. The investigation determined "PIAC Engineering, Quality Control, failed to detect improper assembly of thrust bearing during last overhaul." They stated that following the engine failure, which was first observed at about 90 KIAS, the crew made following omissions in handling the emergency, contrary to standard operating procedures:
The investigation released 11 safety recommendations focussing mainly on maintenance procedures, maintenance quality assurance and regulatory oversight monitoring maintenance.
The pilots' failure to handle the emergency, specifically failing to raise the gear, caused the accident, this being mostly due to inadequacies of PIA pilot training.