AD/PHZL/54 - Hard Alloy Propeller Blades

Overview

The Civil Aviation Regulations 1998, specifically Part 39 - 107, includes Airworthiness Directives designed to address safety concerns in civil aviation. Enacted by the Australian Government, this legislation aims to mitigate risks associated with aircraft components, particularly focusing on the safety of propellers on turboprop aircraft. The directive AD/PHZL/54 targets hard alloy propeller blades manufactured by Hartzell, aiming to prevent the initiation and propagation of corrosion-related cracks, which can compromise flight safety. The policy objective is to ensure that all hard alloy propeller blades are regularly inspected and maintained to prevent service interruptions and potential accidents, thereby safeguarding the integrity and safety of air travel. This legislative instrument was introduced in response to an incident where a significant crack was discovered in a propeller blade, which had originated from a small corrosion pit near the deice boot. The directive mandates rigorous inspection protocols and specific maintenance actions for these blades to ensure they remain airworthy and safe for operation. Compliance with this directive is mandatory, requiring inspections within specified timeframes post-manufacture and at each daily inspection thereafter, with specific attention to the condition of the blade surface and deice boots.

Scope and Application

The Civil Aviation Safety Authority (CASA) Schedule of Airworthiness Directives, specifically AD/PHZL/54, pertains to all turboprop aircraft fitted with Hartzell propeller blades made from hard alloy. This includes aircraft where the hard alloy blades are identifiable by the letter "H" immediately following the blade design number, such as T10282 HB. The directive mandates that blades not painted with Polane paint or those with de-ice boots replaced since manufacture, where it cannot be confirmed that the boots were fitted onto an approved paint surface, must be removed from service and reworked. It further requires a thorough visual inspection of the blades and de-ice boots for any signs of damage or deterioration that might indicate the presence of corrosion beneath the surface. The directive applies nationally across Australia, under the jurisdiction of the Commonwealth of Australia. Compliance with these directives is mandatory, with inspections required within 25 hours after 30 December 1986 and at each daily inspection thereafter. The directive is intended to ensure the continued airworthiness and safety of the aircraft by addressing critical issues such as blade integrity and corrosion protection.

Key Provisions

The Civil Aviation Regulations 1998, under Part 39 - 107, mandate specific safety directives for turboprop aircraft fitted with Hartzell propeller blades made from hard alloy. This is outlined in AD/PHZL/54. The main requirement is that all such blades not painted with Polane paint or those whose de-ice boots were replaced and cannot be confirmed to have been fitted onto an approved paint surface must be removed from service and reworked according to Hartzell Blade Specification Manual 133-( ) and Hartzell SB No 138. All blades must also be anodised before painting, as specified in Section D of Hartzell SB 138. The regulation imposes several obligations on the parties involved. Firstly, within 25 hours of the service after 30 December 1986, the hard alloy blades must be overhauled. Additionally, every 3000 hours of service or five years, whichever comes first, an eddy current inspection must be conducted in accordance with Section V of Manual 133-( ). Daily inspections are also required post 30 December 1986, with particular attention to any blade surface irregularities. Such inspections can be performed by the pilot in command, who must then certify this on the Maintenance Release. Failure to comply with these directives can lead to serious consequences. The regulation states that propellers with blade surface irregularities must be removed from service before further flights and treated in accordance with Para C of Hartzell S.B. 138. This underscores the critical nature of the inspections and the high propagation rate of cracks in these blades. Any non-compliance could result in compromised airworthiness, potentially leading to catastrophic failure during flight. The regulation also mandates that a copy of this Airworthiness Directive be kept in the aircraft and noted on the Maintenance Release as maintenance required.