Key facts
Where to buy| Property | Value | Source |
|---|---|---|
| Composition | Aluminum 2.5–3.5 %, vanadium 2.0–3.0 %, balance titanium | ASTM B265-10 Table 2 (Grade 9) |
| Tubing, annealed | AMS 4943, hydraulic seamless tubing, 3.0Al-2.5V | SAE AMS 4943 (title) |
| Tubing, cold worked and stress relieved | AMS 4944, hydraulic tubing, 3.0Al-2.5V | SAE AMS 4944 (title) |
| Allowables | None in MIL-HDBK-5J (checked); use the AMS minimums or MMPDS | MIL-HDBK-5J |
| Filler (titanium) | ERTi-5, AMS 4954, AWS A5.16, is the titanium rod in the AC table; the manufacturer matches the rod to this alloy | AC 43.13-1B Table 4-15 |
Thicknesses and forms
Tubing is the main aircraft form, to AMS 4943 (annealed) and AMS 4944 (cold worked, stress relieved). Sheet and foil exist in the trade; the public documents here give no specification for them.
Forming
Titanium alloy forming is in three classes: cold forming with no stress relief, cold forming with stress relief, and elevated-temperature forming (built-in relief). The alloy sheet can be formed to a limited extent at room temperature (AMT Handbook, p. 4-85).
Tube bending and flaring follow the aircraft's hydraulic tube manual, not generic rules.
Quick check
Where will you most often meet Ti-3Al-2.5V?
- Fuselage skins
Not this one. No.
- Hydraulic tubing
Best fit. Right.
- Rivets
Not this one. No.
On a real job, the SRM decides.
Welding
Titanium welds need full inert shielding, front and back. Weld repair of hydraulic lines is a procedure in the aircraft manual, not a shop practice (AC 43.13-1B Chapter 4 and the SRM).
Corrosion
Titanium is highly corrosion resistant because an oxide film forms in air. Heated, it shows colour: blue at 700–800 °F, purple at 800–950 °F, gray or black at 1,000 °F or higher; these are protective discolorations and should not be removed (AC 43.13-1B par. 6-181a).
If corrosion occurs it is usually pitting and hard to detect. Titanium is susceptible to hydrogen embrittlement, so chlorinated solvents and chemical corrosion removers are prohibited, and fire-resistant hydraulic fluids must be controlled (AC par. 6-181b and c). Isolate titanium from magnesium, aluminum or alloy steel (AMT Handbook p. 4-85).
Where it is used on aircraft
Hydraulic tube lines on aircraft, to the AMS specs above; the manufacturer's parts list gives the part and the line.
Data sheet
Questions people actually ask
Is Ti-3Al-2.5V the same as Grade 9?
In common usage yes: Grade 9 is the ASTM name for 3Al-2.5V. This page does not give grade strengths because the public sources checked do not carry them.
Limits — when NOT to use this
- No strength values here. The public handbook does not list the alloy.
- Tube replacement is by part number.
Where to buy
Distributors coming soon.
Sources
- FAA AC 43.13-1B CHG 1 — par. 6-181.
- FAA-H-8083-31B, Aviation Maintenance Technician Handbook, Airframe, Volume 1 — pp. 4-85 and 4-86, titanium.
- SAE AMS 4943 and AMS 4944 — titles: annealed, and cold worked stress relieved, seamless hydraulic tubing 3.0Al-2.5V.
- FAA AC 43.13-1B CHG 1 — Table 4-15.
- MMPDS (formerly MIL-HDBK-5) — the current home of design allowables. A repair substantiation cites MMPDS or the SRM, not a website.
- ASTM B265, Titanium and Titanium Alloy Strip, Sheet, and Plate — Table 1 (tensile) and Table 2 (chemical), edition 10 read.