FAA Tells Boeing: Fix Those Loose Engine Bits, Pronto
Published Date: 3/4/2025
Rule
Summary
If you fly or work with Boeing 737 models from the 600 to 900ER series, listen up! The FAA found some engine parts that could come loose and cause serious problems, so they’re requiring fixes like replacing certain fasteners and spacers, plus updating maintenance checks. These changes kick in April 8, 2025, and help keep flights safe without breaking the bank.
Analyzed Economic Effects
6 provisions identified: 1 benefits, 5 costs, 0 mixed.
Mandatory inlet cowl fastener and spacer fixes
If you operate Boeing 737-600/700/700C/800/900/900ER airplanes, the FAA requires replacing specified inlet cowl aft bulkhead fasteners for some airplanes, inspecting and replacing those fasteners if rivets are found for others, and replacing the crushable spacers that attach the inlet cowl to the engine fan case for all airplanes (or optionally installing a serviceable inlet cowl). These actions are required under Boeing Special Attention Requirements Bulletin 737-71-1938 RB, Revision 1, and the AD is effective April 8, 2025.
Must add new airworthiness limitations to maintenance program
Operators must revise their existing maintenance or inspection program to incorporate new airworthiness limitations (AWLs) specified in the AD, and the AD requires incorporation before further flight after the applicable modifications. The FAA estimates revising an operator's maintenance program takes about 90 work-hours, with an average cost of $7,650 per operator.
Aircraft without required hardware can't operate after July 31, 2028
All affected airplanes that have not installed the System Airworthiness Limitation No. 2 and No. 3 hardware modifications cannot operate past July 31, 2028 unless upgraded to new hardware that is fully compliant with Sec. 25.901(c) and Appendix K25.1.1 to Part 25. The AD's Figure 1 explicitly sets July 31, 2028 as the operation cut-off for those unmodified airplanes.
FAA cost estimates for per-airplane work and fleet totals
The FAA estimates this AD affects 1,979 U.S.-registered airplanes. Estimated per-product costs include up to $9,252 for inlet cowl inspection and fastener replacement (up to 98 work-hours x $85 = $8,330 labor plus $922 parts), $16,238 for crushable spacer replacement (16 work-hours x $85 = $1,360 labor plus $14,878 parts), and an option to install a serviceable inlet cowl costing up to $25,490. The FAA estimates total U.S. costs of up to $18,309,708 for the inspection/fastener action and $32,135,002 for the spacer replacement, and $7,650 average per operator to revise maintenance programs.
Deadline for fixes addressing maintenance errors: December 31, 2029
For System Airworthiness Limitation No. 4 (solutions to address potential engine nacelle maintenance errors), operators have until December 31, 2029 to incorporate solutions such as a re-designed fan cowl latch and keeper and high-visibility paint on the integrated drive generator (IDG) door interior. The AD explicitly grants that date for incorporation of those solutions.
Credit if you already performed specified work
If an operator performed the required actions before the AD effective date using Boeing Special Attention Requirements Bulletin 737-71-1938 RB dated July 27, 2023 (as specified in the AD), the operator receives credit for those actions. The AD's paragraph (j) provides explicit credit for previously completed work when it meets the listed conditions.
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If you fly or work with certain Boeing 737 models, listen up! The FAA found some engine parts that could break and cause serious damage, so they’re requiring inspections and fixes by April 8, 2025. This means checking parts, adding safety brackets, or swapping out parts to keep everyone safe and sound—plus updating maintenance plans. It’s a smart move to avoid costly repairs and keep flights smooth and secure.
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