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Installing a Hi-Lok

A Hi-Lok is a threaded pin and a collar. A hex key holds the pin while a tool turns the collar. At a preset torque the wrenching flats shear off, so it cannot be overtorqued and needs no torque check afterwards. The hole decides the job.

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CalculatorHi-Lok Selector: Pin, Grip and CollarHi-Lok pin part number with its grip for your stack, the collars that fit, hex key, shank and oversizes, from the maker's drawings and the FAA…Open the calculator →

The drawing

Where to buy
A Hi-Lok pin and collar in section before and after the wrenching flats shear off
After FAA-H-8083-31B pp. 4-50, 4-51 (Fig. 4-104). Typical only: fastener data give the hole, the grip and the tool.

Step by step

StepActionWhat to do
1Read the dataPin and collar part numbers, grip and hole size come from the drawing or the maker. Hi-Lok calculator.
2Drill to the fitAluminium: interference fit, no more than 0.002 in, to avoid excessive stress round the hole. Steel, titanium and composite: clearance fit.
3DeburrThe pin has a slight radius under the head: deburr the hole edge so the head seats fully.
4Insert the pinFrom the head side. Check grip: pin length to the stack.
5Thread the collarBy hand, recess towards the sheet.
6DriveHex key in the pin, tool on the wrenching flats. Turn until the flats shear off.
7InspectCollar seated, flats gone. No torque inspection needed.
Hi-Lok pin and collar parts
Pin and collar before installation. FAA-H-8083-31B, Fig. 4-104

Tools you need

ToolWhat forBuying guideCatalog
Hi-Lok kitHex keys and bits—17-piece kit
Pins and collarsBy drawingHi-Lok data sheets—

Hi-Lok and Hi-Lite

Hi-Lok

Thread
Standard
Clamp
Higher
Swap
Cannot be replaced with Hi-Lite

Hi-Lite

Thread
About one thread less
Clamp
Lower than Hi-Lok; same shear
Swap
Can be replaced with Hi-Lok for most uses

FAA-H-8083-31B p. 4-51.

What to check when it is done

Look atGoodIf not
HeadFully seatedRadius fouled by a burr: remove and deburr
CollarSeated, flats shearedCheck the grip and hole
Hi-Lok vs Hi-LiteRight collar for the pinCollars do not interchange

Questions people actually ask

Do I need a torque wrench?

Not to install it. The collar shears at its own torque.

Limits of this guide

What the sources support, and no further.

  • The manual governs. Where the SRM, the drawing or the fastener maker says otherwise, follow them; this page explains general practice.
  • Hole sizes and grips are not in the Handbook: use fastener data.

Where to buy

AmericaDistributor coming soonOur partner for this region is on its way
EuropeDistributor coming soonOur partner for this region is on its way
OceaniaDistributor coming soonOur partner for this region is on its way

Distributors coming soon.

Keep going

Calculators

CalculatorHi-Lok Selector: Pin, Grip and CollarPin, collar, hole.CalculatorWhat Drill or Reamer for This Part Number?Type a rivet, CherryMAX, CherryLOCK or Hi-Lok number

Guides

ChartHi-Lok and CherryMAX gripGrip table.

How to do it

Standard practiceDrilling a holeThe hole first.

Data sheets

Data sheetHi-Lok pins and collarsData sheets.

Buy

Distributors coming soon.

Sources

  • FAA-H-8083-31B, Aviation Maintenance Technician Handbook: Airframe, Chapter 4 — p. 4-50, Hi-Lok; p. 4-51, Hi-Lite.
Educational reference only. not approved data. Always consult the applicable SRM, AMM, or AC 43.13-1B and your certifying authority.
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