Foreign object damage
In aviation and aerospace, the term foreign object damage (FOD) refers to any damage to an aircraft attributed to foreign object debris (also referred to as "FOD"), which is any particle or substance, alien to an aircraft or system which could potentially cause damage to it.[1]
External FOD hazards include bird strikes, hail, ice, sandstorms, ash-clouds or objects left on a runway or flight deck. Internal FOD hazards include items left in the cockpit that interfere with flight safety by getting tangled in control cables, jam moving parts or short-out electrical connections.
To jet engines
Jet engines can suffer major damage from even small objects being sucked into the engine. In the United States, the Federal Aviation Administration (FAA) requires that all engine types pass a test which includes firing a fresh chicken (dead, but not frozen) into a running jet engine from a small cannon. The engine does not have to remain functional after the test, but it must not cause significant damage to the rest of the aircraft. Thus, if the bird strike causes it to "throw a blade" (break apart in a way where parts fly off at high speed), doing so must not cause loss of the aircraft.[2]
Engine and airframe designs which avoid FOD
Some military aircraft[
A similar approach is used on many turboshaft-powered helicopters, such as the Mi-24, which use a "vortex-type" or "centrifugal" intake, in which the air is forced to flow through a spiral path before entering the engine; the heavier dust and other debris are forced outwards, where it is separated from the airflow before it enters the engine inlet.
The Russian Mikoyan MiG-29 and Sukhoi Su-27 fighters have a special intake design to prevent ingestion of FOD during take-off from rough airfields. The main air intakes could be closed with mesh doors and special inlets on the top of the intakes temporarily opened. This would allow enough airflow to the engine for take-off but reduced the chances of the engine sucking up objects from the ground.
Another interesting design to minimize the risk of FOD is that of the Antonov An-74, which has a very high placement of the engines.
Boeing offered a gravel runway kit for early 737s that allows the plane to be used from unimproved and gravel runways, in spite of having very low-slung engines. This kit included gravel deflectors on the landing gear; foldaway lights on the bottom of the plane; and screens that prevented gravel, which would enter the open wheelwells when the gear was extended, from hitting critical components. The kit also included vortex dissipators, devices which would reduce the airflow into the engine from the bottom so as to reduce the likelihood of ingesting gravel.
Examples
Vehicle tire track-in
Debris is often trapped in the treads of tires from vehicles coming onto an airfield. Types of debris trapped in a vehicle tire can include rocks, mud, stones, loose hardware (screws, washers, bolts, etc.) and many other forms of small materials. These can be crew and fuel trucks, maintenance vehicles and many others that inadvertently bring debris to a
Runway debris
The crash of a Concorde, Air France Flight 4590, at Charles de Gaulle Airport near Paris on 25 July 2000 was caused by FOD; in this case a piece of titanium debris on the runway which had been part of a thrust reverser that had fallen from a Continental Airlines McDonnell Douglas DC-10 during takeoff about four minutes earlier. The debris strike caused a tire to explode. Rubber debris from the tire struck the wing, rupturing a fuel tank and starting a severe fire leading to loss of control. All 100 passengers and nine crew on board the flight, as well as four people on the ground, were killed. [4]
A Gates Learjet 36A, registration number N527PA, was taking off from Newport News/Williamsburg International Airport in Virginia on March 26, 2007, when the crew heard a loud "pop". Aborting the takeoff, the crew tried to control the "fishtailing" and activate the drogue parachute. The parachute did not work and the Learjet ran off the runway, its tires blown. Airport personnel reported seeing rocks and pieces of metal on the runway after the accident. The National Transportation Safety Board said that the accident was caused by FOD on the runway. Failure of the drogue parachute contributed to the accident.[5]
Volcanic ash
On 24 June 1982,
On 15 December 1989,
Item jettisoned from aircraft
An unusual case of FOD occurred on 28 September 1981 over
Bird strikes
On 20 November 1975 a
On 17 November 1980 a
On January 15, 2009, US Airways Flight 1549 flew into a flock of Canada geese shortly after take off and suffered a double engine failure. The pilot ditched the aircraft in the Hudson River, saving the lives of all on board.
Wildlife and wetlands near airports
Significant problems occur with airports where the grounds were or have become nesting areas for birds. While fences can prevent a moose or deer from wandering onto a runway, birds are more difficult to control. Often airports employ a type of bird scarer that operates on propane to cause a noise loud enough to scare away any birds that might be in the vicinity. Airport managers use any means available (including trained falcons as well as robird flapping-wing falcon-like drones) to reduce bird populations. Another solution under investigation is the use of artificial turf near runways, since it does not offer food, shelter, or water to wildlife.[11]
Conferences
In the United States, the most prominent gathering of FOD experts has been the annual National Aerospace FOD Prevention Conference. It is hosted in a different city each year by National Aerospace FOD Prevention, Inc. (NAFPI), a nonprofit association that focuses on FOD education, awareness and prevention. Conference information, including presentations from past conferences, is available at the NAFPI Web site.[12] However, NAFPI has come under some critique as being focused on tool control and manufacturing processes, and other members of the industry have stepped forward to fill the gaps. BAA hosted the world's first airport-led conference on the subject in November 2010.[13]
Detection technologies & FOD prevention
There is some debate regarding FOD detection systems as the costs can be high and the domain of responsibility is not clear. However, one airport claims that their FOD detection system may have paid for itself in a single incident where personnel were alerted to a steel cable on the runway, before a single aircraft was put at risk.[14] The FAA has investigated FOD detection technologies, and has set standards for the following categories:[15]
- Radar
- Electro-optical (visible band imagery (standard CCTV) and low light cameras)
- Hybrid
- RFID on metal
- Manufactured FODS Mats - Track-Out Prevention & Track-In Control
Damage tolerance improvements
The negative effects from FOD can be reduced or entirely eliminated by introducing compressive residual stresses in critical fatigue areas into the part during the manufacturing process. These beneficial stresses are induced into the part through cold working the part with peening processes: shot peening, or laser peening. The deeper the compressive residual stress the more significant the fatigue life and damage tolerance improvement. Shot peening typically induces compressive stresses a few thousandths of an inch deep, laser peening typically imparts compressive residual stresses 0.040 to 0.100 inches deep. Laser peen induced compressive stresses are also more resistant to heat exposure.
Technologies, information and training materials helpful in preventing FOD
- Aerospace tool control systems
- FOD prevention program manuals
- Magnetic bars
- Promotional and awareness materials
- Tool and parts control/retrieval
- Tow-behind friction sweeperbetter source needed]
- Tow-behind sweepers
- Training materials
- Vacuum truck sweepers
- Walk-behind sweepers
- FOD prevention matsbetter source needed]
Economic impact
Internationally, FOD costs the aviation industry US$13 billion per year in direct plus indirect costs. The indirect costs are as much as ten times the direct cost value, representing delays, aircraft changes, incurred fuel costs, unscheduled maintenance, and the like.[18] and causes expensive, significant damage to aircraft and parts and death and injury to workers, pilots and passengers.
It is estimated that FOD costs major airlines in the United States $26 per flight in aircraft repairs, plus $312 in such additional indirect costs as flight delays, plane changes and fuel inefficiencies.[19]
"There are other costs that are not as easy to calculate but are equally disturbing," according to UK Royal Air Force Wing Commander and FOD researcher Richard Friend.[20] "From accidents such as the Air France Concorde, Flight AF 4590, there is the loss of life, suffering and effect on the families of those who died, the suspicion of malpractice, guilt, and blame that could last for lifetimes. This harrowing torment is incalculable but should not be forgotten, ever. If everyone kept this in mind, we would remain vigilant and forever prevent foreign object debris from causing a problem. In fact, many factors combine to cause a chain of events that can lead to a failure."
Studies
There have only been two detailed studies of the economic cost of FOD for civil airline operations. The first was by Brad Bachtel of Boeing, who published a value of $4 billion USD per year.[1] This top-down value was for several years the standard industry figure for the cost of FOD. The second work (2007) was by Iain McCreary from the consultancy Insight SRI Ltd. This more detailed report offered a first-cut of the cost of FOD, based on a bottom-up analysis of airline maintenance log records. Here, data was broken into per flight direct costs and per flight indirect costs for the top 300 global airports, with detailed footnotes on the supporting data.[21] The Insight SRI research was a standard reference for 2007-2009 as it was the only source presenting costs and thus was quoted by regulators, airports, and technology providers alike.[22]
However, while that 2007 Insight SRI paper remains the best free public source of data, the new analysis (2010) from Insight SRI offers new numbers. The author of the new report (not free) says "Readers are cautioned not to rely on or in the future refer to numbers from the 2007-08 Insight SRI paper The Economic Cost of FOD to Airlines. This earlier effort was 'The' first document detailing the direct and indirect cost of FOD that was based on airline maintenance data (the entire document was a single page of data, followed by 8 pages of footnotes)."
Per-flight direct costs of $26[21] are calculated by considering engine maintenance spending, tire replacements, and aircraft body damage.
Per-flight indirect costs include a total of 33 individual categories:
- Airport efficiency losses
- Carbon / environmental issues
- Change of aircraft
- Close airport
- Close runway
- Corporate manslaughter/criminal liability
- Cost of corrective action
- Cost of hiring and training replacement
- Cost of rental or lease of replacement equipment
- Cost of restoration of order
- Cost of the investigation
- Delay for planes in air
- Delays at gate
- Fines and citations
- Fuel efficiency losses
- Hotels
- In-air go-around
- Increased insurance premiums
- Increased operating costs on remaining equipment
- Insurance deductibles
- Legal fees resulting
- Liability claims in excess of insurance
- Loss of aircraft
- Loss of business and damage to reputation
- Loss of productivity of injured personnel
- Loss of spares or specialized equipment
- Lost time and overtime
- Missed connections
- Morale
- Reaction by crews leading to disruption of schedule
- Replacement flights on other carriers
- Scheduled maintenance
- Unscheduled maintenance
The study concludes that when these indirect costs are added, then the cost of FOD increases by a multiple of up to 10 times.[23]
References
- ^ a b "Foreign Object Debris and Damage Prevention". Boeing Aero Magazine. Retrieved 2008-10-28.
- ^ "FAA Advisory Circular" (PDF). Archived from the original (PDF) on 2017-04-09. Retrieved 2008-03-27.
- ^ "Airbus MoU with IAI to explore eco-efficient 'engines-off' taxiing". 17 June 2009. Retrieved 2009-07-30.
- ^ "'No time': Chiling final words of Concorde pilot". News.com.au. 2023-04-21. Archived from the original on 2023-04-22.
- ^ "NTSB Final Report, Accident No. NYC07LA087".
- ^ List of ejections from aircraft in 1981. Archived 2017-04-21 at the Wayback Machine Retrieved: 30 August 2008.
- ^ Page with link to WMV clip of destruction of TA-4J BuNo. 156896. Retrieved 30 August 2008.
- ^ AAIB Official Report of the investigation into the crash of HS.125-600B registration G-BCUX retrieved 2010-05-19.
- ^ Aviation Safety Network XV256 accident page retrieved 2008-01-23.
- ^ "RAAF Exchange Pilot Valour Cited in RAF Accident Report", "Newsdesk - Military", Australian Aviation magazine No. 16, September 1982, p45. Aerospace Publications Pty. Ltd., Manly NSW
- ^ "Airside Applications for Artificial Turf" (PDF). Federal Aviation Administration. 2006.
- ^ "nafpi.com - Domain Name For Sale". DAN.COM.
- ^ "BAA Global FOD Conference". BAA London Heathrow Airport. Archived from the original on 2013-01-25. Retrieved 2010-12-02.
- ^ "YVR Airport". TV Interview. Archived from the original on 2012-03-03. Retrieved 2009-07-30.
- ^ "FAA Advisory Circular" (PDF). Retrieved 2009-09-21.
- ^ "Foreign Object Debris (FOD) Sweeper | FOD BOSS | Aerosweep". aerosweep.
- ^ "FODCheck.com | FOD Prevention Mat System". www.fodcheck.com/.
- ^ "Runway Safety - FOD, Birds, and the Case for Automated Scanning". Insight SRI Ltd. Retrieved 2010-12-02.
- ^ "The Economic Cost of FOD to Airlines" (PDF). Insight SRI Ltd. Archived from the original (PDF) on 2012-12-24. Retrieved 2008-10-29.
- ^ Make It FOD Free website
- ^ a b "The Economic Cost of FOD to Airlines". Insight SRI Ltd. Archived from the original on 2009-07-07. Retrieved 2008-10-28.
- ^ "Search". www.eurocontrol.int. Retrieved 2020-08-17.
- ^ "The economic cost of FOD to airlines" (PDF). Insight SRI Ltd. March 2008. Archived from the original (PDF) on 2022-03-02. Retrieved 2010-09-21.
External links
- Media related to Foreign object damage at Wikimedia Commons