31 July 2011 C1 CIVIL AVIATION DEPARTMENT HONG KONG ...

AIRWORTHINESS NOTICE NO. 12APPENDIX NO. 68Issue 230 September 20061 BackgroundFOREIGN OBJECT DAMAGE TO AIRCRAFT AND ENGINES1.1 Experiences learnt from a foreign CAA that they continue to receive reports ofdamage to aircraft and engines caused by foreign objects. Foreign ObjectDamage (FOD) presents a serious airworthiness threat to any aircraft not tomention the economic impact on the operator. In extreme cases, FOD canlead to an accident and loss of life. FOD damage to airframes and enginescan be extremely expensive to rectify and may result in the aircraft beingremoved from revenue service for significant period of time. There arenumerous reports on record of FOD damage to engines (in particular rotatingassemblies), nose and main landing gear assemblies and aircraft structure.1.2 A research project led by the foreign CAA revealed that a continuing threatexists from varying amounts of FOD present on aircraft maintenance areas andairport manoeuvring areas, including stands, aircraft taxiways and runways.The study showed the aircraft themselves as the main cause of FOD on therunway and this poses the highest immediate risk. Here, parts of aircraftbecome detached or tools and equipment, inadvertently left in the aircraft fallout during takeoff or landing. The largest item found on a runway was awheel chock but metal panels and honeycomb structure were also amongst thelarger items. The FOD found on taxiways and stands came mainly fromairport vehicles and the equipment they tow such as baggage trolleys, steps,cargo equipment etc. The size and shape of some of these foreign objectsmake it likely to cause tyre damage and subsequent tyre burst. The cleaningof aircraft cabins and the transfer of waste from cabin to airside rubbishcontainers is also seen to be a common source of foreign objects in the standareas. Other typical foreign objects consist of such items as oil cans,spanners, pliers, torches, suitcase items (both internal & external), mobileradios, aircraft catering equipment, cutlery, landing gear ground lock pins,thrust reverser lock-out pins and broken parts of ground servicingequipment/vehicles.1.3 Smaller items could be ingested by an engine. In many cases, FOD damageto engine rotating assemblies has led to vibration leading to air turn-backs,diversions and subsequent engine replacement. Boroscope inspections ofengines following reports of engine surging very often reveal internal damageto the enginesuch damage can of course be very expensive to repair.Typically, damage to the aircraft can range from damage to horizontalstabilizer leading edges to pressure hull penetration by objects thrown up fromthe runway, to varying degrees of damage to landing gear assemblies andAN-12 A68 P.130 September 2006