It's more bad news for Southwest Airlines as it has been revealed some of its aircraft have been identified to have pickle fork cracks. The discovery has caused the American airline to ground two of its Boeing 737 NG aircraft.

Pickle forks on Southwest Airlines aircraft

The issue was reported to the FAA and Boeing on Tuesday this week. A spokesperson for the airline told KOMO News that the cracking was found during an examination of all its Boeing 737 NG in compliance with an Airworthiness Directive issued by the Federal Aviation Administration (FAA). The spokesperson confirmed:

"During our inspections of the high-cycle NGs, we did not find abnormalities on the vast majority of our inspected fleet but did identify signs of cracking on two aircraft. Southwest removed the aircraft from our operation and reported the findings to Boeing and the FAA. The aircraft will remain out of our schedule until the maintenance items have been fully resolved, and we do not have a return to service timeline for the aircraft."

The issue with pickle fork cracks is that the entire structural integrity of the aircraft is at risk. It was essential for Southwest Airlines to remove these aircraft since pickle fork cracking can cause additional stress, torque and improper management of aerodynamic forces. Had this issue not been detected, the results of pickle fork breakage could have been catastrophic.

How will this impact Southwest?

This development in the tale of the Boeing 737 does not bode well for Southwest. It has already experienced cancellations of an estimated 30,000 flights since the 737 MAX grounding which it says has cost its members around $100 million.

What will this mean for Southwest's services? Photo: Alan Wilson via Flickr

The grounding of two of Southwest's 737 NG appears to be a repeat of the bad luck it has already faced thanks to Boeing. The grounding will see flights canceled, schedules reshuffled as well as likely paying for replacement aircraft or pickle fork repairs.

But already the 737 pickle fork directive has cost the airline. A 2-hour inspection and subsequent report are estimated to cost about $170 per aircraft. And Southwest Airlines says its Technical Operations team still have more aircraft to investigate.

It is not yet clear which of Southwest Airlines' 737 NG have been removed from service or how many of the four pickle forks have been identified on each aircraft as cracked. Southwest Airlines have not issued a statement about the case.

The grounding has already cost the airline and there is uncertainty about the future. Photo: Colin Brown Photography via Flickr

The FAA's pickle fork directive

The FAA last week issued an Airworthiness Directive for 1,911 aircraft to be examined with potential pickle fork issues. Cracks were identified in the pickle fork component on a Boeing 737 NG during a passenger to freighter conversion. It was reported to Boeing and the FAA and proved not to be an isolated instance. Pickle fork cracks were then identified on numerous other aircraft including Southwest's own.

The FAA's directive was issued for Boeing 737-600, -700, -700C, -800, -900, and -900ER series aircraft. Those which had completed 30,000 flight cycles were to be examined within seven days. The pickle fork - the component attaching the wing structure to the main aircraft fuselage - is manufactured to last 90,000 flight cycles. But issues have now been found on aircraft which have done far less mileage.

Southwest operates some 752 Boeing 737 according to Planespotters.