Building on last night’s post about the criteria for inspection, Boeing has released details about its service bulletin (SB) issued last night that covers 175 737-300s, -400s and -500s.
UPDATE 6:03 PM: Here’s my complete story on the service bulletin and here’s the full text of the FAA emergency airworthiness directive.
Here are the quick facts:
- The SB requires inspection of the lower row of fasteners in the lap-joint, along the left and right-hand side of the crown of the aircraft at stringer four between Station 360 and 908, making the area under scrutiny about 50ft long.
- This SB applies to line numbers 2553 through 3132, which were delivered between 1993 and 2000, which had a frame tear strap spacing of 20 inches.
- Of the 579 aircraft produced, only about 175 have 30,000 cycles or more.
- Inspections must take place within 5 days on a portion of the 175 that have 35,000 cycles or more.
- Inspections will be required within 20 days of the remaining balance of the 175 aircraft with between 30,000 and 34,999 cycles.
- Around 80 of the 175 are in the US, with the majority flying with Southwest Airlines.
- Inspections will be repeated every 500 cycles until a more permanent solution can be identified as a result of the NTSB investigation.
- Line numbers 292 through 2552 had a different lap joint design, which Boeing says included a frame tear strap spacing of 10in. That design already fell into a lap-joint modification program that came in to effect for those aircraft over 50,000 cycles.
- For line numbers 2553 through 3132, Boeing said it anticipated cracks in this area of the fuselage, but not until 60,000 cycles or more.
This post was originally published to the internet between 2007 and 2012. Links, images, and embedded media from that era may no longer function as intended.
This post originally appeared at Flightglobal.com from 2007 to 2012.