Identifying Prop Strikes: Defining their Occurrence

Identifying Prop Strikes: Defining their Occurrence

In the world of propeller-driven aircraft, propeller strikes are a costly and potentially dangerous occurrence. These incidents, which involve the propeller impacting a solid object, can range from causing minor engine damage to catastrophic failures [1].

Common causes of propeller strikes often stem from sudden stoppages, impact with objects such as the ground or obstacles, or loss of propeller blade tip during operation [1]. High-energy scenarios like porpoising, wheelbarrowing during landing, or improper approach speeds increase the risk of propeller strikes [5].

Symptoms indicative of a prop strike include sudden stoppage or abrupt engine torque change, visible damage to the propeller blades, engine vibration or unusual noises, and possible oil leaks or pressure drops [1]. It is crucial to note that any decision to continue operating an engine after a prop strike or sudden stoppage must not be taken without a thorough teardown inspection [1].

Following a propeller strike, recommended inspections include a complete engine teardown and internal inspection, a detailed propeller examination, verification of engine oil system integrity, and compliance with any specific Airworthiness Directives or Service Bulletins relevant to the engine or propeller model involved [1]. These inspections are crucial because continuing to run an engine after a prop strike without disassembly risks catastrophic failure and loss of safety [1].

Deer strikes, as shown in videos, can cause damage to the propeller and the side of the aircraft, requiring an engine tear-down [1]. Wildlife on the runway is another major prop strike concern, especially during sunrise, sunset, and nighttime hours [1].

It is essential to carefully check the propeller for damage during pre-flight, looking for dents, unusual scratches/scrapes, warping, grass stains, damage to the tip, etc. [1]. The risks of prop strikes are high, and there is no clear, quantifiable threshold for measuring engine damage [1].

Lycoming Service Bulletins 475C and AD Note 91-14-22 require a mandatory inspection and compliance with repair and reassembly procedures for any engine involved in sudden stoppage, propeller strike, or loss of prop blade tip without disassembly and inspection [1].

The individual circumstances of a propeller strike can't always predict the extent of interior engine damage, and future reliability of the engine is a major concern [1]. It is crucial to remember that even the slightest damage to a propeller can signal engine damage, leading to an engine failure [1].

In summary, propeller strikes usually stem from landing mishaps or sudden stoppages, show clear physical and operational symptoms, and always require comprehensive teardown inspections before further operation, as mandated by Lycoming and aviation safety authorities [1][5]. Adhering to these safety measures can help ensure the continued safety and reliability of propeller-driven aircraft.

[1] Lycoming Service Bulletin 533C [2] Lycoming Service Bulletin No. 475C [3] AD Note 91-14-22 [4] Lycoming Inspection Checklist After a Propeller Strike [5] FAA Advisory Circular 25-11B, Propeller-Driven Airplane Operations

1. In thepropeller-driven aircraft industry, incidents of aircraft propellers striking solid objects can lead to costly damages and potential dangers, ranging from minor engine damages to catastrophic failures.
2. Sudden stoppages, impact with the ground or obstacles, and loss of propeller blade tips during operation are common causes of propeller strikes.
3. High-energy scenarios like porpoising, wheelbarrowing during landing, or improper approach speeds increase the risk of propeller strikes, which can have symptoms such as sudden stoppage, engine vibration, visible propeller blade damage, or unusual noises.
4. Continuing to operate an engine after a prop strike without thorough teardown inspection is risky, as it might lead to catastrophic failures and loss of safety.
5. Following a propeller strike, recommended inspections include a complete engine teardown and internal inspection, a detailed propeller examination, verification of engine oil system integrity, and adherence to any specific Airworthiness Directives or Service Bulletins relevant to the engine or propeller model.
6. Deer strikes and wildlife on the runway are significant concerns during sunrise, sunset, and nighttime hours, as they can cause propeller damage.
7. During pre-flight, it is essential to carefully check the propeller for damage, looking for dents, unusual scratches/scrapes, warping, grass stains, damage to the tip, etc.
8. The individual circumstances of a propeller strike can't always predict the extent of interior engine damage, and future reliability of the engine is a major concern.
9. Adhering to inspection guidelines, such as Lycoming Service Bulletins 475C and AD Note 91-14-22, which require mandatory inspections and compliance with repair and reassembly procedures for engines involved in sudden stoppages, propeller strikes, or loss of prop blade tip without disassembly and inspection, is crucial for ensuring the continued safety and reliability of propeller-driven aircraft.

Read also: