The reference to Torque 1558 primarily appears in aviation regulatory documentation, specifically within Federal Aviation Administration (FAA) Airworthiness Directives (ADs) concerning Piper Aircraft. "Room 1558" is the physical location where these specific "torque-related" directives and their reference documents were historically held for examination. Context of Torque 1558 In the context of FAA Airworthiness Directive
(located at 601 E. 12th Street, Kansas City, Missouri) was the designated office for examining technical documents regarding Piper Aircraft Corporation Model PA34
The term "torque" in this specific regulatory guide refers to the rudder torque tube fitting . These directives were issued to prevent: Failure of the torque tube fitting. Possible loss of rudder control.
Technical Guide: Inspecting and Maintaining Torque Tube Fittings
Based on the safety requirements outlined in related FAA directives like AD 92-08-04
, follow these steps for managing torque tube fittings in compatible aircraft: Material Identification
Inspect the rudder torque tube fitting to determine if it is made of torque 1558
This is critical as specific models (like the Piper PA34-200 series) required replacements if certain aluminum fittings were found to be susceptible to failure. Visual Inspection for Integrity
Check for signs of fatigue, cracks, or corrosion on the fitting.
Ensure the security of the attachment points to the rudder and control cables. Compliance with Service Bulletins Refer to the Piper Service Bulletins
mentioned in the directive for specific torque values and replacement procedures. Documentation Examination
Historically, official copies of these directives and the "torque" related technical documents could be examined at the FAA Central Region Office, Room 1558 General Torque Concepts (Physics)
If your inquiry relates to the physical principle of torque rather than the aviation directive, torque ( ) is calculated using the formula: The reference to Torque 1558 primarily appears in
cap M equals r cross cap F cross sine open paren theta close paren (Radius/Lever Arm)
: The distance from the axis of rotation to the point where force is applied. : The magnitude of the force applied. : The angle between the force and the lever arm (typically 90 raised to the composed with power for maximum efficiency). specific aircraft model mentioned in these directives or a deeper dive into torque physics
"Torque 1558" refers to critical technical applications in specialized engineering, including Rotax-Owner discussions on engine gear reduction boxes, hydraulic motor calculations, and research on high-torque wind turbines in MDPI's Energies. These contexts highlight the importance of torque in maximizing efficiency, whether for aircraft propulsion, heavy machinery, or renewable energy generation. For more details on gear reduction, visit Rotax-Owner.
Norbar, a UK-based world leader in torque tools, produces a line of professional torque wrenches that often feature model numbers including 1558. A typical Norbar reference might be:
If you search for torque 1558 Norbar, you will likely find a "break-over" or "click-type" wrench known for its accuracy to ±3%. This is a mechanic's tool, not a hydraulic industrial tool.
Some 1558 specifications are actually a two-step process: torque to 500 lb-ft, then tighten an additional 90 degrees. The final peak torque may reach 1558 lb-ft, but the spec is angle-controlled. If you simply dial 1558 lb-ft on a wrench, you will miss the required bolt stretch. The Norbar 1558 Series Norbar, a UK-based world
At 1558 Nm, a steel shaft with a diameter of 50mm experiences a shear stress of approximately 127 MPa, which is well within the yield strength of hardened alloy steel (400+ MPa), but close to the limit for standard carbon steel. This means any system requiring torque 1558 must use heat-treated 4140 or 4340 chromoly steel, or aerospace-grade alloys.
No major torque wrench brand (Snap-on, CDI, Norbar, Proto, Armstrong, Tekton) lists a “1558” model. Check:
To understand torque 1558, we must first establish the unit of measurement. In engineering notation, torque is force multiplied by distance.
For the remainder of this article, we will focus primarily on 1558 Nm, as this is the most common engineering interpretation of an unlabeled "torque 1558" specification in global markets.
A torque specification of 1,558 lb-ft is not something you will find on a passenger car. You will find this figure in:
At 1,558 lb-ft, you cannot use a standard hand wrench. Achieving this torque requires:
Example application: A 1.5-inch diameter stud on the flange of a large industrial gearbox may require a final torque of 1,558 lb-ft to achieve the proper clamp load, ensuring no oil leaks under high vibration.
If you search industrial catalogs for "torque 1558," you might find a hydraulic torque wrench model. For example, the Hytorc Stealth 2 can achieve 1,558 Nm (1,149 lb-ft) for bolting wind turbine tower flanges.