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Newton Aero 300 - Locking And Non Locking Fuel Cap

Select Cap Style:
Locking Cap Non-Locking Cap


These English fuel caps are used on most of the worlds super cars and bikes, and some series production aero planes. They are beautifully made in forged and bright anodized aluminum. The high precision and easy to operate mechanism is very secure and non vented. They are designed to keep the fuel in and the water out. The lock is there to ensure that your tank is free from contaminants. Aero caps are used on Adam, CAP, Cirrus, Diamond, Lancair Columbia, Lancair kits, Nemesis, Vans, Velocity and many more aircraft.

Two keys come with the locking version (L). Fixing can be by rivet, bolt, weld or glass in as appropriate. These are flush caps of outstanding quality which are ideal for virtually any homebuilt aircraft.

The 300 Series: 3-3/4" OD opening 1-3/4", 6 hole 3" pcd. A37 fits 2" and 2.25" Hoses.

*Note: Options Standard No-Lock (S) or Locking (L)
California Prop 65 Warning Symbol

WARNING: The product may contain and/or expose you to a chemical(s) or substance(s) which are known to the State of California to cause cancer and/or birth defects or other reproductive harm.


  • Centre-Forging: Aluminium Alloy 6082
  • Neck: Aluminium Alloy 6082/T6
  • Option: Black
  • Neck: Polished

  • No Lock: 136.6 g
  • Locking: 154.5 g

  • Outside Diameter (A): 62.5 mm
  • Outside Diameter (B): 58.4 mm
  • Bolt Circle Dia.: (PCD) Not Applicable
  • Bore: 44.5 mm
  • Overall Height : 33.75 mm

Neck Options:
  • Spigot: 58.0 mm A3NLP (Lock, steel neck)
  • Body Diameter: G 58.0 mm A3NLPB (Lock, steel neck, black)
  • Neck Diameter: Not Applicable
  • Flange Thickness: Not Applicable


Worked great on my SR22

Robbey B Verified Purchase


November 11, 2022

Excellent English quality. Stock varies and shipping can be delayed so plan ahead. Repair kits also available through Spruce. Highly recommend.

Alex N
September 3, 2020

Im happy this fit, disappointed i wasnt able to order a cap that matches the key i already have. If that were an option, i would have gone that route and ended up with a 5 start review. As it stands, this is a good and functional stop-gap measure.

Justin C Verified Purchase


December 30, 2021


Please note, Aircraft Spruce's personnel are not certified aircraft mechanics and can only provide general support and ideas, which should not be relied upon or implemented in lieu of consulting an A&P or other qualified technician. Aircraft Spruce assumes no responsibility or liability for any issue or problem which may arise from any repair, modification or other work done from this knowledge base. Any product eligibility information provided here is based on general application guides and we recommend always referring to your specific aircraft parts manual, the parts manufacturer or consulting with a qualified mechanic.

Q: Can you get replacement keys? My plane has the lock cap but never got the keys and previous owner doesn't have them. #609

Yes you would order our part number 05-04542.

Q: Can I order a pair of caps with two identical lock picks? I need a pair of caps with one key for a pair of caps

Yes. We can special order matched lock caps from the vendor. Please contact a sales rep, to help you with this order.

Q: Whats the difference between the Newton aero 200 & 300? Is it that the 200 is not a vented cap and the 300 is vented? Thanks

The difference is the size of the filler cap, the aero 200 is smaller.

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