FAA Orders 787 Wing Fuel Tank Sealant Inspections
AD 2026-22-05, effective 7 December 2026, requires sealant inspection and adhesion tests on certain Boeing 787-8, 787-9 and 787-10 airplanes after skipped production checks.
Organizational byline
Updated November 2, 2026
5 min read
The FAA has adopted AD 2026-22-05 for certain Boeing 787-8, 787-9 and 787-10 airplanes. The directive was published in the Federal Register on 2 November 2026 and is effective 7 December 2026. It requires a detailed inspection of specified sealant, an adhesion test, and on-condition repairs.
The FAA says the AD was prompted by a report that, during production, certain sealant installations inside the center wing fuel tank did not receive the required visual and adhesion inspections. The unsafe condition the agency describes is the potential for sealant defects. If those defects are not addressed, the FAA says they could create an ignition source inside the fuel tank volume and a risk of a fuel tank explosion during a lightning strike.
This is a fuel-system rule in the same season as the October 737 fuel-shutoff-panel gasket directives, on a different airplane and a different defect. Those 737 actions concern access-panel gaskets. AD 2026-22-05 concerns production inspections of structural sealant in the 787 wing side-of-body area.
What operators must do
Applicability is not every 787. The AD applies to the 787-8, 787-9 and 787-10 airplanes identified in Boeing Alert Requirements Bulletin B787-81205-SB570053-00 RB, Issue 001, dated 5 November 2025. The subject code is ATA 57, Wings. The amendment is 39-23507, Docket No. FAA-2026-1322.
The incorporated bulletin specifies a detailed inspection for sealant defects and surface depression defects, plus an adhesion test, on identified sealant in the left, right and center wing side-of-body areas and the area between the side-of-body rib and rib 2. On-condition actions include contacting Boeing for repair instructions and performing the repair. Where the bulletin dates compliance from its own issue date, the AD substitutes the 7 December 2026 effective date.
Two clarifications in the final rule will matter in the tank. The adhesion test of injection sealant follows the dashed lines in the bulletin figure, and the sealant-to-substrate transition is inspected with that test. Sealant repairs that comply with airworthiness limitations 28-AWL-83, 28-AWL-120, 28-AWL-121, 28-AWL-123, 28-AWL-124 and 28-AWL-125, as applicable, in Boeing document D011Z009-03-04, dated August 2018, are acceptable without a separate alternative-method approval. Maintenance-manual procedures may be used for removal and replacement only if those limitations are met.
The FAA also said the AD is limited to airplanes that lack evidence the production inspections were done, and that sealant inspections inside the center wing tank are being performed on airplanes outside the applicability. The rule text did not change for that comment.
The FAA's U.S. cost estimate
The FAA estimates that the AD affects 60 airplanes of U.S. registry. The compliance action in the cost table is a detailed inspection and adhesion test of the sealant, at 34 work-hours times $85 per hour, or $2,890 per airplane, with no parts cost in that estimate. The estimated cost on U.S. operators is $173,400. The agency says it has no definitive data for the cost of on-condition repairs, and that the manufacturer indicates some or all of the AD costs may be covered under warranty.
Those figures are the FAA's U.S. compliance estimate. They are not a count of the worldwide 787 fleet, and they do not include the repair labour if adhesion or visual checks find defects.
Same-day companion on the 747 stabilizer tank
A separate final rule in the same Federal Register issue, AD 2026-22-04 (amendment 39-23506, Docket No. FAA-2026-7215), is also effective 7 December 2026. It supersedes AD 2023-07-09 and applies to Model 747-400 and 747-8 series airplanes identified in Boeing Alert Requirements Bulletin 747-28A2373 RB, dated 6 November 2025.
AD 2023-07-09 already required wear inspections of the stabilizer-tank transfer-pump inlet check valves and impeller inlet adapters, plus an installation limit. AD 2026-22-04 makes those inspections repetitive. From 7 December, a Crane Aerospace Hydro-Aire stabilizer-tank pump housing, inlet check valve, or impeller may be installed only if the check valve and inlet adapter have been inspected and found serviceable under the new bulletin.
The unsafe condition the FAA describes is wear between the inlet check valve and the inlet adapter that can develop an ignition source in the horizontal stabilizer fuel tank. Combined with flammable fuel vapors, the agency says that could result in a fuel tank explosion and loss of the airplane. The FAA calls the new AD an interim action. It says the main and center wing tanks use the same pump design but are not currently subject to the same unsafe condition because of pump shutoff logic. Further rulemaking is possible if later analysis changes that assessment.
The FAA estimates 31 airplanes of U.S. registry. Each inspection cycle is estimated at 18 work-hours, or $1,530, for the two inlet check valves, and the same again for the two impeller inlet adapters. Special flight permits are allowed only if the horizontal stabilizer fuel tank is defueled and both transfer-pump circuit breakers are locked open.
What to watch
- Which line numbers fall inside the 787 bulletin. The production-inspection gap is defined by the requirements bulletin, not by a blanket 787-8/9/10 effectivity.
- On-condition repair volume. The FAA did not estimate repair cost. A high defect rate would move the work from a 34-hour inspection into tank entry and sealant restoration under the fuel-system airworthiness limitations.
- Whether the 747 action stays limited to the stabilizer tank. The FAA has already flagged the shared pump design on the main and center tanks as a possible later rulemaking question.
AD 2026-22-05 and AD 2026-22-04 both take effect on 7 December 2026. The records check against the Boeing effectivity lists can start before that date.
