Heli Austria and Heli Werk are offering an EASA approved upgrade that replaces the main ship NiCad battery of the Airbus EC135 with a True Blue Power lithium-ion battery, and the weight saving is stated as up to 19.8 kg, about 44 pounds. Heli Austria developed the supplemental type certificate and Heli Werk makes the upgrade kit. The report of the approval, published on 12 October 2026, gives one weight figure in its text and a different one, 19.4 kg, in its subheading.
What is approved
The upgrade offers two batteries, the TB30 with a 30 amp hour capacity and the TB40 with 40 amp hours, and both are available for all EC135 models, including those with Helionix avionics. The kit includes the battery, an installation kit and the STC documentation. The stated benefits are lower weight, higher capacity and reduced scheduled battery maintenance, the last in the words of Heli Werk’s managing director.
| Item | TB30 | TB40 |
|---|---|---|
| Capacity | 30 Ah | 40 Ah |
| EC135 models covered | All, including Helionix | All, including Helionix |
| Weight saving versus NiCad | Up to 19.8 kg, depending on battery configuration | |
The weight number, checked
The conversion works: 19.8 kg is 43.7 pounds, the “about 44 pounds” in the report, while 19.4 kg would be 42.8 pounds, so the subheading and the text cannot both be the saving. The text figure is paired with the qualifier that it depends on the battery configuration, which means 19.8 kg is a maximum and not a typical value.
Published True Blue Power product information gives the TB40 as 36.6 pounds, or about 16.6 kg, with a nominal 40 amp hour capacity at 23°C, described as up to 60 percent lighter than lead acid and NiCad alternatives. If that weight applies to the EC135 installation, a saving of 19.8 kg implies a NiCad battery of about 36.4 kg, so the lithium ion unit would be about 54 percent lighter, inside the manufacturer’s up to 60 percent. That is an inference from two separate documents, and the installation weight including mounting hardware and harness is not given.
The report does not say which battery or configuration produces the 19.8 kg. Because the TB30 has the smaller capacity, the largest saving presumably belongs to it, but that is an expectation and not a published pairing. An operator choosing between the two would be trading amp hours against weight, and the figures for that trade, for each battery on this airframe, are not in the report.
What the manufacturer claims for this battery family
The TB20, TB30 and TB40 are the company’s fifth generation main ship batteries, introduced in 2019 as its first on condition, engine start lithium ion batteries, meaning the battery indicates when attention is needed, including at the end of its useful life. The company has also published an operating range of minus 40°C to plus 70°C for its batteries and describes them as TSO certified. Those are manufacturer statements, made in marketing material for other aircraft, and the report of the EC135 approval does not restate them for this installation.
What is not disclosed
The report gives no price, no number of kits sold or planned, no STC number and no baseline for the NiCad capacity the lithium ion battery replaces, so the claim of higher capacity cannot be put in amp hours. The reduced scheduled maintenance is described without an interval, and the report does not describe how the installation handles a thermal event, which is the main airworthiness question for lithium ion batteries on aircraft. For operators, the practical numbers still missing are the kit price, the installation labor and the maintenance saving per year.
The status is simple. The upgrade is available now, according to the developers, and no deadline or delivery schedule is given. The check for operators is the STC itself: its approved configurations, any conditions on EC135 variants and the instructions for continued airworthiness. For another lithium ion safety question treated with data, see the 1:20 hydrogen leak study. Sources: report of the EASA approval, 12 October 2026, with statements by Heli Austria and Heli Werk; True Blue Power product information for the TB30 and TB40.
Add EnergyNews.biz as a preferred source on Google
