Fishpole Hoist Maintenance

Fishpole Hoists are specialized, single attachment point hoists used extensively in the aviation industry for close-quarter lifting. They are specifically designed for tight and hard to reach locations where other types of hoists cannot be used. Fishpole hoists are usually operated by a crank and gear type handle instead of the usual lever or hand chain on most hoists, and due to their fishing pole resemblance, they are called Fishpole hoists. Due to its design, fishpole hoists enable rapid installation and removal of aircraft components.

 

Custom-designed Fishpole Hoists are used for specific Aircraft models for the removal or installation of APU (auxiliary power units), inboard and outboard flap actuators, and various engine and cabin accessories by the “bootstrap method.” Fishpole hoists are available in both manual and powered versions. Most models are equipped with a telescoping barrel and allow for the interchangeability of attachment point assemblies, providing flexibility for multiple lifting applications. Additionally, due to their application feasibility and durability, fishpole hoists are often certified as a standard hoisting mechanism by OEMs for maintenance.

 

Hoist Working Principle and Types:

A hoist is a suspended machinery unit used to lift or lower a freely suspended (unguided) load. By leveraging small force over a long distance and transforming it to a large force over a short distance, hoists can accomplish heavy suspensions that would otherwise be impossible. Hoists are classified into three types depending on the powering mode: Hand Chain-Operated hoists, Electric-powered hoists, and Air-powered hoists. The selection of hoist type depends on the lifting load, locational constraints, speed of operation, and power (AC/DC) availability.

 

Hand Chain Operated Hoist:

Also called Manual hoists, they operate by pulling a continuous hand chain suspended from the hoist, which turns a series of interwoven links – axles, gears, and sprockets. As the operator pulls the hand chain, power is transmitted through the hoist gear to the load chain sprocket to lift or pull the aircraft load. The lifting speed and effort are dependent on the gear ratio of the hoist. To ensure the safety of the load and personnel operating the hoist, manual hoists are integrated with a braking system to prevent the load from slipping back. Hand Chain operated hoists are divided into two types: Lever chain and Hand chain. Although the operational principle is the same, Lever chain hoists require only one hand to operate, and a hand chain requires both hands to work. Hand chain hoists are ideal for lifting high vertical loads, and Lever chain hoists are preferred for lifting horizontal, angled, and low vertical loads.

 

Electric Powered Hoists:

Electric hoists operate with motors attached to a solid load-bearing structure parallel to the ground level (steel beam) to lift weights. A basic electric hoist consists of a motor, braking mechanism, and ropes to lift the weight. The motor is operated by a wired or wireless handheld controller for vertical load movement. Complex electric hoists contain a series of motors to lift weights more than 1000lbs and traverse loads in a two-dimensional vertical plane. Electric hoists are safer than hand-held hoists as the operator is far from the vicinity of operation. Failure of ropes or braking mechanism will not result in an injury or causality.

 

Air Powered Hoists:

Pneumatic hoists also operate using differential air pressure to move the chain or rope attached to the load. Compared to Electric hoists, Pneumatic hoists are slower but are positionally accurate. These hoists are ideal for fine-tuning the movement of components before final installation and induces less stress on the parts while lifting and suspending them. In areas where electricity use is considered hazardous (locations that use explosion-proof equipment), pneumatic hoists are the ideal choice. They occupy less space than electric hoists and can be fit into tight and inaccessible areas.

 

Applications of Fishpole Hoist:

Fishpole hoists are used to lift and suspend several aircraft components such as APU, Batteries, Condensers or reheaters, engine handling equipment, shackle and sling assembly, Power drive unit, and hydraulic actuators.

 

Maintenance and Calibration of Fishpole Hoist – Why is it Essential:

American National Standard (ASME) B30.16 has laid out standards for hoist maintenance and inspection. According to ASME standards, the following three types of hoist maintenance is critical and should be carried out for the safety of personnel and the suspended load:

 

 

  1. Normal Hoist service (less than 65% of rated load) – Monthly inspection
  2. Heavy Hoist service (greater than 65% of rated load) – Weekly to monthly inspection
  3. Severe service (Maximum or up to 100% of rated load) – Daily to weekly inspection

 

 

The Following are the Periodic inspection intervals according to ASME:

 

The list of components and tests to be carried out during Prestart, Frequent and Periodic inspections are laid out in the ASME B30.16 standards. It is recommended that Hoist inspections be performed by certified personnel. In addition, more frequent maintenance inspections should be made if the hoist has been subjected to adverse environmental conditions or excessive use or overloading.

 

Fishpole Hoist Load test:

ASME B30.16 laid out standards that new, altered, or repaired fishpole hoists and the hoists scheduled for annual inspection should be Load tested by designated personnel before the hoist is placed under service. Procedure to be followed during Operational test or Load test for fishpole hoist is as follows:

 

Step 1:

Lifting and lowering functions shall be tested under no-load conditions (testing through complete rated lift length is not required).

Step 2:

After testing under no-load conditions, a load of at least 50 lb (23 kg) times the number of load-supporting parts of the chain shall be applied to the hoist, and the hoist shall be tested to check proper load control.

Step 3:

Gradual increase of load up to 100% of the rated load of the hoist or more than 125% of the rated load of the hoist unless otherwise recommended by the hoist OEM.

 

The load test is termed successfully if the hoist operates normally at the full load test. The hoist is then inspected to ensure that the full load did not cause additional damage to the lifting components. Post-inspection, a written report should be prepared and recorded to provide documentation that it was completed. Markings or labeling on the hoist of the testing date are also often used to identify the load test verification.

 

Cumulative defects in fishpole hoist components can often result in operational uncertainties leading to Catastrophic failures, downtime, and maintenance losses. Preventive maintenance and Calibration avoid these errors, ensure components’ accuracy for sustained and repeated, and enhance the service life of fishpole hoists. In addition, following a regular and timely calibration schedule ensures accuracy of measurement and improves the service efficiency and accuracy.

 

e2b calibration offers industry-leading ISO-certified fishpole hoist maintenance and calibration services. Our labs are ISO/IEC 17025 accredited and operated by a team of qualified calibration experts to test and calibrate your hoists. Our verifiable services are unmatched in the industry. We are registered with ANAB. We are also ANSI/NCSL Z540-1-1994 certified. We have the NIST Traceable Wide scope of ISO/IEC 17025 accreditation. Contact e2b calibration for all your equipment calibration needs. a

 

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