AD 94-03-11
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Hartzell Propeller, Inc. | HC-B4MN-5 | HARTZELL PROPELLER INC. Model HC-B4 Series Propellers |
| aircraft | Hartzell Propeller, Inc. | HC-B4MP-3 | HARTZELL PROPELLER INC. Model HC-B4 Series Propellers |
| aircraft | Hartzell Propeller, Inc. | HC-B4TN-3 | HARTZELL PROPELLER INC. Model HC-B4 Series Propellers |
| aircraft | Hartzell Propeller, Inc. | HC-B4TN-5 | HARTZELL PROPELLER INC. Model HC-B4 Series Propellers |
| aircraft | Hartzell Propeller, Inc. | HC-B4TW-3 | HARTZELL PROPELLER INC. Model HC-B4 Series Propellers |
| aircraft | Hartzell Propeller, Inc. | HC-B4W40-2 | HARTZELL PROPELLER INC. Model HC-B4 Series Propellers |
Unsafe Condition
Fatigue cracks in propeller hub arm assemblies progressing to failure, resulting in hub arm and blade departure and potential engine separation and loss of aircraft control.
AI-generated summary from the source AD text. Verify against the official source before acting.
Required Actions
Determine if the propeller hub arm assembly has been installed on a Mitsubishi MU-2B series aircraft and check its serial number against Hartzell ASB A186 Table 1. Remove and inspect/rework affected assemblies per ASB A186, with specific compliance schedules based on time in service or blade strike history. Reinstall serviceable assemblies with required markings.
AI-generated summary from the source AD text. Verify against the official source before acting.
Compliance Time
Compliance required within the next 300 hours time in service (TIS), next scheduled overhaul, or 24 calendar months after the effective date (February 28, 1994), whichever occurs first for assemblies with ≥3,000 hours TSN. For <3,000 hours TSN, comply prior to 3,300 hours TSN, next scheduled overhaul, or 24 calendar months. Blade strike cases require compliance within 100 hours TIS or 2 calendar months, or prior to further flight if post-effective date blade strike.
AI-generated summary from the source AD text. Verify against the official source before acting.
Affected Aircraft
Hartzell Propeller Inc. HC-B4 series propellers (models HC-B4MN-5, HC-B4MP-3, HC-B4TN-3, HC-B4TN-5, HC-B4TW-3, HC-B4W40-2) except those on Mitsubishi MU-2B-26A, -36A, -40, -60 aircraft. Installed on various aircraft including Beech King Air, CASA C-212, Dornier DO228, Embraer EMB-121A1, Fairchild SA226-TB, Let L-410A, Shorts SC-7 series 3 variant 200.
AI-generated summary from the source AD text. Verify against the official source before acting.
Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
This site is not affiliated with or endorsed by the FAA. Always verify with official sources.