The United States Air Force has announced that over 40 per cent of its fleet of F-15 combat jets will remain grounded for the foreseeable future.
The announcement came after the discovery of manufacturing defects within the aircrafts' airframes that have been in place for almost 30 years.
As described by USAF officials in a statement issued on the 10th January, 162 F-15 Eagles have flawed metal beams - flaws including insufficient width and rough finish. The demands of military flight for the past three decades, they added, have acted to highlight the issue.
F-15 Grounding Ordered After November 2007 Crash
The whole issue concerning the safety of the F-15 - a highly successful military aircraft in service with Japan and Saudi Arabia as well as the US - really began with an incident involving a C- model which took place in November 2007. The aircraft involved crashed during the course of a training flight - ripping in two and causing a type-wide grounding to be imposed.
The measure has been selectively lifted and re-imposed as more facts have emerged during the course of the post-crash investigations. Recently, the F-15E Strike Eagle variants were permitted to fly, but restrictions were still in place for F-15s A- through to D-.
Then, several days ago, 261 of the grounded aircraft were cleared to take to the skies.
Liability Issue Enters F-15 Safety Investigations
Now, the officials said, the issue of possible liability in respect of aircraft manufacturing firm Boeing is being assessed. Boeing took over McDonnell-Douglas - the F-15's producer - a decade ago. However, it has not yet been established whether MDD actually made the parts in question, or whether they were produced by an external source.
Paul Guse, spokesman for Boeing, has stated that "the appropriate parties" will take on any potential liability issues, adding: "it would be inappropriate for Boeing to speculate or discuss those issues at this time."
The 162 defective F-15s were all manufactured during a seven year period ending in 1985.
A number of the defective beams - 'longerons', as they are known - are very close to the correct profile. However, stated the officials, no chances are being taken, on the basis that any one of the 162 aircraft could suffer the same fate as the example that crashed.
F-15s Could be Repaired or Replaced
Two choices now exist. While the longerons could be replaced, the aircraft could alternatively be abandoned entirely and themselves replaced by examples of the F-22 Raptor - the USAF's latest military combat aircraft which recently reached the level of Full Operational Capability.
The USAF Air Combat Command's head, General John D.W Corley, advised media representatives gathered at the Pentagon on the 10th January that the F-15's issues constituted a "crisis" affecting the country's "workhorse" military combat jet tasked with national defence duties.
No pattern, he said, could be identified to link the flaws, given the wide span of years over which the affected models were made.
"This is not isolated," he stated. "This is systemic."
Source - Armed Forces International's Aviation Expert
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