EASA AD US-2018-03-13
SUPERSEDED BY FAA AD 2023-21-07
Summary
FAA Airworthiness Directive 2018-03-13 is a final rule addressing certain General Electric Company CT7 series turboprop engines, specifically models CT7-5A2, CT7-5A3, CT7-7A, CT7-7A1, CT7-9B, CT7-9B1, CT7-9B2, CT7-9C, and CT7-9C3 with main propeller shaft part number 77581-11 installed. This directive mandates initial and repetitive visual and fluorescent-penetrant inspections of the main propeller shaft to detect wear, corrosion, and cracks. It was issued to prevent unsafe conditions resulting from main propeller shaft failure.
What Changed
This AD introduces mandatory inspection requirements for the main propeller shaft on specified GE CT7 turboprop engines, including visual and fluorescent-penetrant inspections. It adds upper limits to inspection intervals to avoid conflicting inspection times and requires cleaning and inspection within specified time frames for propeller gearboxes with high time since new. This is a new regulation rather than an amendment.
Why It Matters
The directive is critical for aviation professionals because failure to detect cracks or corrosion in the main propeller shaft could lead to in-flight propeller separation, loss of engine thrust control, and potential damage to the aircraft. Operators and maintenance organizations must comply to ensure flight safety and avoid costly incidents. Compliance helps maintain airworthiness and prevents unexpected engine or propeller failures.
What To Do
Affected operators must perform cleaning, visual inspections, and fluorescent-penetrant inspections of the main propeller shaft within 150 hours time in service or one month after the effective date for gearboxes with 46,000 hours TSN or more. Repetitive inspections must continue as specified in the AD. Comments on the AD were invited until March 30, 2018, but the directive was effective February 28, 2018.
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