Accident of PIA Flight PK-661 ATR 42-500 AP-BHO Near Havelian on 7th December, 2016
1. On December 7, 2016, a PIA ATR 42-500 (AP-BHO) flying from Chitral to Islamabad crashed near Havelian killing all 47 souls on-board. Safety Investigation Board (SIB) of Pakistan was mandated by the Federal Government to carry out detailed investigation into this unfortunate air crash.
The investigation is towards a concluding stage, however, some important findings of technical nature require immediate attention/intervention.
These are as follows:
(a) Sequence of events was initiated with dislodging of one blade of power turbine Stage-1 (PT-1), inside engine number one (left-side engine) due to fatigue.
(b) This dislodging of one blade resulted in in-flight engine shut down and it contributed towards erratic/abnormal behavior of engine number one propeller.
(c) According to Service Bulletin these turbine blades were to be changed after completion of 10,000 hours on immediate next maintenance opportunity. The said engine was under maintenance on November 11, 2016, at that time those blades had completed 10004.1 hour (due for change). This activity should have been undertaken at that time but itwas missed out by the concerned.
(d) Aircraft flew approximately ninety-three hours after the said maintenance activity, before it crashed on December 7, 2016.
(e) Missing out of such an activity highlights a lapse on the part of PIA (maintenance and quality assurance) as well as a possible in-adequacy/lack of oversight by Pakistan CAA.
2. In light of the above, following is recommended please:-
(a) PIA is to ensure immediate implementation of said Service Bulletin in letter and spirit on the entire fleet of ATR aircraft, undertake an audit of the related areas of maintenance practices, ascertain root cause(s) for the said lapse, and adopt appropriate corrective measures to avoid recurrence.
(b) Pakistan CAA is to evaluate its oversight mechanism for its adequacy to discover lapses and intervene in a proactive manner, ascertain shortfall(s) and undertake necessary improvements.