Airworthiness Directives; Hoffmann GmbH & Co. KG Propellers

FAA / Federal Register · 2021-26365

The FAA is superseding Airworthiness Directive (AD) 2020-25-05 for all Hoffmann GmbH & Co. KG (Hoffmann) model HO-V 72 propellers. AD 2020-25-05 required amending the existing aircraft flight manual (AFM) with abnormal propeller vibration instructions. AD 2020-25-05 also required visual inspection and non-destructive test (NDT) inspection of the propeller hub and, depending on the results of the inspections, replacement of the propeller hub with a part eligible for installation. AD 2020-25-05 also required replacement of the propeller hub before exceeding 30 years since the date of manufacture. This AD was prompted by reports of cracks at different positions on two affected propeller hubs and subsequent manufacturer revision of the service information, which showed that the 30-year life limit of the propeller hub is no longer needed. This AD requires amending the existing AFM by inserting abnormal propeller vibration instructions, visual inspection and NDT inspection of the propeller hub and, depending on the results of the inspections, replacement of the propeller hub with a part eligible for installation. The FAA is issuing this AD to address the unsafe condition on these products.