For the second time this month, the United States Air Force has decided to ground hundreds of its older Boeing Co. (NYSE: BA) F-15 fighter jets. Yesterday it grounded 452 of the fighters in its continued investigation into an accident earlier this month that has exposed some flaws in the planes.

Yesterday's grounding represents approximately 60% of the entire F-15 fleet, and the Air Force has stated that each and every plane will remain grounded until they can all be individually inspected and possibly repaired. Earlier this month, the entire fleet had been grounded, and was only put back into service on the 21st.

The problems first surfaced when Missouri Air National Guard training exercise went wrong. In the accident, the pilot was able to safely eject from the plane before crashing. Investigations into the accident have revealed flaws in the planes fuselage. Specifically, metal rails that hold the fuselage together.

The Air Force investigation has decided there are "possible fleet-wide airworthiness problems".

Shares of Boeing are trading up 0.2% on the day to $93.80, up $0.19.

[photo: JMZawodny]

Michael Fowlkes has worked as a stock trader for seven years and spent the last two years working as an analyst for the online investment advisory service Investor's Observer.