Xinda Knowledge: Application of Portable Boring Machines in Aircraft Landing Gear Maintenance

An aircraft landing gear is one of the components subjected to the most complex loads during takeoff and landing. Positions such as retraction hinge points, piston rod lugs, and strut pin holes endure long-term impact loads, making pin holes prone to ovalization, scoring, and wear deviation. Under the traditional workflow, such parts often have to be removed and shipped to a specialized overhaul facility for large-scale boring machines — long lead time, with logistics and lifting costs both significant. In recent years, portable boring processes have begun to be tried in aviation maintenance (especially in general aviation, regional aircraft, military field maintenance, and MRO outsourced bays) — bringing the boring machine to the hangar or field, and doing on-site hole alignment, build-up weld, and re-boring in situ.

Although Xinda's portable boring machine series (XDT40/50, XDT50 integrated weld-bore, XDT60, XDT90, XDT110, XDT150) primarily serves construction machinery, marine, steel, and mining, the process logic carries over. Below we discuss model selection and process thinking when applying such equipment to landing gear maintenance scenarios.

I. What Jobs Does Boring Do in Landing Gear Maintenance?

Landing gear has quite a few "hole series"; typical categories include:

Main strut / side strut hinge holes:​ diameters mostly in the 40–80 mm range; after wear, handled by build-up weld + re-bore, or oversize bore + bushing insert.

Piston rod lug pin holes:​ slightly larger diameter, often 50–100 mm; lug wall thickness is limited, so coaxiality and surface roughness requirements are higher.

Torsion arm connection holes, lock strut pin holes:​ smaller diameter but numerous; suited to small-diameter boring bar with one setup, machining multiple holes in sequence.

II. Matching Xinda Boring Models by Hole Diameter Range

The hole diameter span in landing gear maintenance isn't particularly wide — 40–150 mm basically covers most lugs and hinge points, corresponding to these Xinda models:

(Article illustration -1)

The XDT50 integrated weld-bore machine deserves special attention in landing gear maintenance​ — it integrates "hole welding + boring" into one unit, welding range 50–230 mm, single-side weld thickness 4–5 mm, paired with MIG350/MIG500 gas metal arc welders. When lug wear is modest, you build up and re-bore in situ directly after welding, saving one teardown / setup and tool referencing cycle.

III. Several Process Key Points for On-Site Landing Gear Boring

1. Centering takes more time than cutting

Portable boring mounts into the hole via a centering cone + support seat. Landing gear lugs have thin walls and low L/D ratio; the centering cone must be sized correctly, with front/middle/rear supports stabilized at three points if possible. The XDT series comes standard with 2 support seats + centering cone; for deep holes you can add a "bearing pad support seat" (this part is included with the XDT50 weld-bore combo).

2. Weld – bore in one clamping

If a landing gear pin hole is built up and then removed / transferred / re-aligned for boring, coaxiality can drift. With the XDT50 weld-bore combo, you don't move the machine after welding — just swap the tool post and go into boring. Coaxiality stays steadier and time is saved.

3. Coaxial hole series in one setup

If the front and rear hinge points of a main strut require coaxiality, you can follow the XDT series logic of "multiple holes side by side, one-time positioned machining" — run the long boring bar through, bore the front hole without removing the machine, then slide-feed directly to bore the rear hole.

4. Surface roughness and roundness

Xinda XDT series machining roundness can reach 0.02–0.05 mm (model dependent), roughness Ra 3.2. For landing gear pin holes fitted with spherical plain bearings or bronze bushings, this indicator is generally sufficient; positions mating with sealing rings can get one more finishing pass.

IV. A Few Reminders for Maintenance Crew / Repair Engineering Handover

First verify bore diameter + depth + lug spacing:​ XDT40/50 max travel is 260–380 mm; for long strut-type holes confirm it's enough — if not, go non-standard with extended boring bar.

Power supply conditions:​ XDT40/50 runs on 220V single-phase, easy to connect in a hangar; XDT60 hydraulic power pack is 18.5 kW, XDT90 servo version needs 380V — field ops need a generator.

Aviation scenarios recommend test blocks:​ before the first piece, run portable boring parameters (RPM, feed, depth of cut) on a test block of the same material, measure roundness, roughness, and bore allowance, then go to the actual part.

Landing gear is a high-safety-critical component​ — any on-site boring repair process must first be approved by the repair station's maintenance manual / EO (Engineering Order). Equipment is just a tool; process approval is the prerequisite.

Portable boring is still far from "mainstream" in aviation circles, but there have been plenty of trials in general aviation periodic inspections, field emergency repairs, military field maintenance, and some MRO outsourced stations. Taking the "build-up weld — re-bore — coaxial positioning" logic that's proven in construction machinery, then tuning parameters to match landing gear material and tolerance requirements — there's actually quite a bit it can do.

(This article is compiled from publicly available corporate materials and industry information, for reference only. Specific product information and service terms are subject to the official release of the company.)