2026-07218Proposed Rule

FAA Mandates Rust Checks for Chinook-Like Helicopters

Published Date: 4/14/2026

Proposed Rule

Summary

If you own or operate Columbia Model 234 or Restricted Category CH-47D helicopters, listen up! The FAA wants you to regularly check certain flight control parts for rust and fix or replace them if needed to keep flying safe. You’ll also need to report what you find, and some parts won’t be allowed unless they meet new rules—all to keep your chopper in top shape without breaking the bank.

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Analyzed Economic Effects

5 provisions identified: 0 benefits, 5 costs, 0 mixed.

Fix or replace corroded connecting links

If inspections find light or moderate corrosion you must repair the primer defects or remove/repair the corrosion using FAA-approved methods before further flight; if inspections find severe corrosion (greater than 0.005 inches) you must remove the connecting link and replace it with a serviceable part. On-condition costs are estimated at $170 labor to remove corrosion per link, and replacing a link can cost up to $2,705 per link (including parts and 2 work-hours).

Mandatory borescope inspections every cycle

If you operate a Columbia Model 234 or Restricted Category CH-47D helicopter with the listed connecting links, you must do a borescope inspection within 30 days after the AD becomes effective and then repeat inspections at set intervals: no more than 24 months if no corrosion, 18 months for light corrosion, and 12 months for moderate corrosion. Corrosion levels are defined in the rule as less than 0.001 inches (light), 0.001–0.005 inches (moderate), and greater than 0.005 inches (severe).

Limit on installing certain part-numbered links

After the AD effective date, you may not install connecting links with part numbers P/N 145C3340-1, -2, -7, -8, -9, -10, -11, or -12 on any helicopter unless the part is "serviceable" (inspected and repaired as required by the AD, or new with zero hours).

No special flight permits allowed

The AD states that special flight permits under 14 CFR 21.197 and 21.199 are not allowed, so you cannot use a special flight permit to move a helicopter that has the affected connecting links for the purpose of compliance. This restriction applies as soon as the AD is effective.

Mandatory reporting to FAA for inspection results

You must report the results of each borescope inspection to the FAA within 30 days after each inspection (or within 30 days after the AD effective date for the first report), and you must submit reports for that initial report plus three subsequent inspection/reporting intervals (four reports total). Each report is estimated to take about 1 work-hour (estimated paperwork burden 1 hour per response).

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Key Dates

Published Date
Comments Due
4/14/2026
5/29/2026

Department and Agencies

Department
Independent Agency
Agency
Transportation Department
Federal Aviation Administration
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