Next: Classic Elliptical Parachutes

ASTM F3322-18 Parachute Certification and the FAA Waiver FAQ

© 2020 - Fruity Chutes Inc.

We get a lot of questions about using our parachutes and other UAV / drone products in order to get an FAA waiver or international CAA approval for flight over people.

This FAQ will help answer many of the questions about ASTM F3322-18 testing standards which the FAA may ask for.

This will also address questions regarding the drone, drone weight and how each can affect the waiver process or availability.

Has Fruity Chutes already tested their parachute recovery systems (PRS) to the ASTM F3322-18 standard?

No! The ASTM standard is not just for us as the parachute manufacturer to test and meet the standard. The ASTM standard is designed for testing and certification of the complete system: both the Fruity Chutes PRS and the drone it's used with. It’s this combined solution that is tested to the standard and certified. The certification is not valid with a different combination of PRS, or drone.

Does testing need to be done for each drone and PRS system sold?

No. The testing is done using representative samples of the complete system and this is what's tested for certification. Also the testing is done at both minimum and maximum weights and over a range of flight conditions and payload options.

Who does the testing; does the Parachute Manufacturer or Drone Manufacturer do their own testing?

Neither. Testing is done at an FAA authorized third party testing authority (TPTA). There are a number of these across the US, mostly associated with the various FAA testing sites. The nearest one to us is in Nevada. Of course, before testing, the drone manufacturer and the parachute manufacturer should have already done their own testing per the standard to be sure to pass the TPTA suite of testing. Testing is expensive.

What information and testing does the ASTM Standard require?

It requires:

  • A tranche of documentation that needs to be provided to the TPTA as called out by the ASTM standard.
  • Materials and strength information about the PRS is provided by the Parachute Manufacturer. A key factor is strength information about the parachute and whether it is strong enough to not break under any deployment conditions.
  • Flight testing through a suite of different flight types, failure scenarios, at minimum and maximum weights to cover payload options (cameras, sensors, etc). For multi-copter drones, the minimum number of flights is 45 flights. There are 9 different flight scenarios and failure conditions tested, with 5 tests each. There needs to be 5 successful flights in a row to pass a particular test. If one flight fails, then the five need to be redone.

What is the result of the TPTA?

A detailed report written by the TPTA combined with the documentation together with the flight testing results. Key results would include:

  • All the various documents used for the ASTM certification.
  • Specifics on the drone tested, with min / max weights, or optional payloads that are tested for.
  • Specifics on the PRS, parachute size and type, and how it is mounted and any connections to the drone.
  • Testing will determine the certified minimum flight altitude that is required when flying over people.

After testing, how does one get a waiver?

When applying to the FAA for your waiver, they will ask for proof of safety of the drone and PRS. You would then provide the ASTM certification report as proof of the safety of the drone with the PRS.

What features does the PRS need to include for the standard?

The PRS must have:

  • A parachute
  • Some way to launch or eject the parachute
  • Harnesses and rigging to connect the parachute to the drone
  • An Autonomous or Automatic Trigger System (ATS). This device automatically detects a drone failure and ejects the parachute. The Fruity Chutes SATS-MINI is an example of an ATS. Automatic parachute ejection software (parachute channel) in the autopilot cannot be used on it’s own. The ATS must be able to operate independently of the autopilot in case the autopilot fails. The autopilot parachute channel out can be combined into the ATS so both systems can initiate the parachute ejection.
  • A secondary radio should also be provided so the pilot in command (PIC) can also eject the parachute if needed.

Does the drone have any special requirements to meet the standard?

In an ideal world, yes! The ASTM specification called out these requirements, most all of which are missing on most commercial drones like DJI, or Yuneec:

  • A place or way to mount the PRS on the drone. For most drones this is relatively easy to work around.
  • Hard-points where the parachute recovery harness allows connections to the drone. Many times the best hard points are the rotor booms.
  • Drone's primary power source as an input to the ATS so the voltage can be monitored. Not available in most commercial drones. Easier with open source drones.
  • Low voltage 5V power source to keep the ATS battery charged and to provide secondary power. Pixhawk can provide this via an Aux channel output.
  • An input to the drone to provide flight termination so the rotors can immediately stop when the parachute is ejected. NOTE: This is the single largest issue with most all commercial drones that use closed source autopilots, like DJI’s A3, Yuneec, etc. Open source autopilots like the Pixhawk platform using PX4 have a flight termination auxiliary input capability. We are working to get the Ardupilot to provide similar functionality.

It is generally more challenging to properly integrate a PRS with commercial/prosumer drones while fully complying with the ASTM standard. In some cases it’s not possible. Regardless, the FAA is accepting ASTM certifications where this is documented in the TPTA report as not being met. The single more important safety issue is stopping the rotors when the parachute ejects, and this is a very challenging issue to work around for many commercial drones.

What else does the FAA consider in order to issue a Flight or People Waiver?

Any drone and parachute system can be ASTM certified regardless of size and weight, but the certification on its own does not mean you can get a waiver. The FAA is also going to consider the impact energy the drone would have when using a parachute. In an FAA NPRM, the FAA defined three categories of drone weight and impact energy that could be considered for a waiver grant.

In the document, the FAA breaks out three categories of waivers and under what conditions the drone needs to meet. There is also a lot of other information in this document.

Category 1

The FAA determined that small unmanned aircraft weighing less than 0.55 pounds (250 grams) pose a low risk of injury when operating over people. Accordingly, Category 1 is simple and straightforward: operators would be able to fly small unmanned aircraft weighing 0.55 pounds or less over people. While these operations would be subject to all of the existing requirements governing small UAS operations in part 107,12 the FAA does not propose any additional restrictions as a condition of flying over people.

Category 2

This would provide flexibility for operators who wish to conduct operations over people using unmanned aircraft that weigh more than 0.55 pounds. Unlike Category 1, Category 2 is not solely weight-based. The FAA proposes a set of performance-based requirements that would allow a small unmanned aircraft to operate over people if the manufacturer can demonstrate that, if the unmanned aircraft crashed into a person, the resulting injury would be below a certain severity threshold. The waiver granted for Category 2 is unrestricted operations over people. For this category the landing impact energy must be under 11 ft-lbs (14J) of impact energy.

As an example, let’s look at the Mavic 2 at a weight of 850 grams and using a IFC-30-SUZ chute. At this weight, we would have a descent rate of 3.74 m/s. Using the formula J = ½ * M * V^2 the calculated impact energy is 5.94J (J is Joules, M is mass in Kg, V is velocity in meters per second). A Mavic 2 meets this requirement very easily. Even the Phantom Pro series and similar size drones meet this requirement, but possibly with a larger parachute.

Category 3

This allows for a higher injury threshold than Category 2, but it also limits an individual’s exposure to the risk of injury through operational limitations - meaning this is not for unrestricted use. For this category, the landing impact energy must be under 25 ft-lbs (33J) of impact energy. The waiver granted for Category 3 is restricted operations over people.

The Inspire 2 drone might be an example of a Category 3 waiver drone, but only if using a large 72” D parachute in order to get the impact energy under the impact energy limit. Getting a 72” parachute on an Inspire 2 is difficult. The I2 would be considered at the upper limits on what is practical for Category 3 use.

Above Category 3

It’s not clear under what conditions the FAA would grant a waiver over the Category 3 limit. This affects most all so-called delivery drones, LIDAR drones and other heavy lift drones.

What is the status of Fruity Chutes parachutes certifications for various drones?

Where we are at varies with the different drones.

DJI Drones Mavic 2 Pro and Zoom

We currently have a project in place to certify this drone with our parachute systems. We already have a parachute system for the M2, but the challenge is stopping the rotors when the parachute ejects. We are working on a device that attaches to the drones rotors to stop these when the parachute deploys. Timeline is 3 to 4 months. We may do a Kickstater campaign once we get close to help fund the certification process, which is quite expensive.

Mavic Pro

There is a 50/50 chance we will do this drone as well. It would be after the Mavic 2 drone has been certified since the rotor stop device would be very similar.

Inspire 2

The issue with certifying this drone is the weight. The Inspire 2 sits right at the upper limit of the Category 3 waiver described above. We may not certify this drone unless there is a compelling business case.

Other Drones

We sell parachute systems to many manufacturers of drones using Pixhawk or other open source, or proprietary autopilots. It’s up to these manufacturers to perform the certifications with our support. We have several customers who have gone through this process with our products.

April 2, 2020