Source : http://www.nzherald.co.nz/nz/news/article.cfm?c_id=1&objectid=10648349
30 May 2010 - Aircraft was overdue for safety checks
A Great Barrier Airlines plane engine was overdue for a maintenance check when its propeller came off in flight and smashed the passenger cabin window. The dramatic July 2009 accident, detailed this week in a Transport Accident Investigation report, forced the plane to return to the island's Claris airfield where three passengers were treated for minor injuries. And it followed a mass of problems with the airline dating back to 1997, according to previously undisclosed Civil Aviation Authority correspondence. The Herald on Sunday received the documents under the Official Information Act. The CAA initially refused to hand over the material, citing commercial sensitivity. It took eight months and the intervention of the Ombudsman before they were released. According to the reports, there was another incident involving one of the airline's flights in which a plane's engine lost power and the aircraft was forced to make an emergency landing - the second time the plane had suffered such a problem. The airline's chief executive, Gerard Rea, based on the island, has failed to respond to repeated calls for comment. The airline's entire fleet of 14 aircraft was grounded by the CAA in June 1998. The newly-released documents reveal that inspectors found poor staff attitudes to safety and incorrect and illegible flight duty records that had been altered without authorisation. The CAA's director at the time, Kevin Ward, said the action was taken due to "critical deficiencies" in maintenance and pilot training, aircraft flying with known defects and suspected false records. After the planes were allowed back in the air, the CAA instituted regular indepth audits and inspections. But there were more problems:
* Three passengers were injured when the propeller came off a four-engine Trislander in July last year.
* A Piper Cherokee 6 crashed into a swamp moments after take-off in September. The pilot was hospitalised with leg injuries and passenger Jodee McKay suffered a broken pelvis and broken rib.
* A twin-engine Partenavia P68B had to make an emergency landing in November.
The Trislander engine had been purchased from an Indonesian company, which provided Great Barrier Airlines with inaccurate maintenance records. It came with a flight record stating the engine had accrued 47.4 hours flying time since its previous overhaul. But it was probably almost 440 hours.
propeller assembly, near Claris, Great Barrier Island, 5 July 2009
Findings are listed in order of development and not in order of priority.
3.1 The engine propeller assembly separated from the right engine of ZK-LOU in flight and struck the fuselage when the crankshaft failed at the flange that connected it to the propeller hub.
3.2 High-cycle fatigue cracking on the flange that had developed during normal operations from undetected corrosion had reached a critical stage and allowed the flange to fail in overload.
3.3 The crankshaft had inadvertently passed its overhaul service life by around 11% when the failure occurred, but the company had not realised this because of an anomaly in the recorded overseas service hours prior to importation of the engine to New Zealand. Ordinarily, the crankshaft would have been retired before a failure was likely.
3.4 The crankshaft was an older design that has since been progressively superseded by those with flanges less prone to cracking.
3.5 There was no requirement for a specific periodic crack check of the older-design crankshaft flanges, but this has been addressed by the CAA issuing a Continuing Airworthiness Notice on the issue.
3.6 The CAA audit of the company had examined whether its engine overhaul periods were correct, but the audit could not have been expected to discover the anomaly in the overseas-recorded engine hours.