Lightning Protection

FAR 23.2515 — Lightning Protection

FAR 23.2515 requires IFR-approved Part 23 airplanes to protect critical electrical and electronic systems from lightning strikes. Learn what it means.

In Plain English

FAR 23.2515 sets lightning protection standards for Part 23 airplanes approved for IFR operations. Because IFR flight routinely exposes aircraft to convective weather and electrical activity, the FAA requires designers to assume lightning exposure is realistic — unless the applicant can show otherwise.

The rule splits electrical and electronic systems into two tiers based on how critical they are:

Safety-critical systems (failure would prevent continued safe flight and landing) must be designed and installed so that:
- The function is not adversely affected during or after a lightning strike, and
- The system recovers normal operation in a timely manner after exposure (unless recovery would conflict with other system requirements).
Capability-critical systems (failure would significantly reduce airplane capability or the crew's ability to handle adverse conditions) must be designed so the function recovers normal operation in a timely manner after a lightning strike.

Operationally, this is why modern IFR-certified airplanes have shielded wiring, bonded structures, and hardened avionics — so a strike doesn't take out your attitude reference, autopilot, or engine controls when you need them most.

Regulation Text

14 CFR § 23.2515

§ 23.2515 Electrical and electronic system lightning protection. An airplane approved for IFR operations must meet the following requirements, unless an applicant shows that exposure to lightning is unlikely: (a) Each electrical or electronic system that performs a function, the failure of which would prevent the continued safe flight and landing of the airplane, must be designed and installed such that— (1) The function at the airplane level is not adversely affected during and after the time the airplane is exposed to lightning; and (2) The system recovers normal operation of that function in a timely manner after the airplane is exposed to lightning unless the system's recovery conflicts with other operational or functional requirements of the system. (b) Each electrical and electronic system that performs a function, the failure of which would significantly reduce the capability of the airplane or the ability of the flightcrew to respond to an adverse operating condition, must be designed and installed such that the system recovers normal operation of that function in a timely manner after the airplane is exposed to lightning.

Oral Exam Questions a DPE Might Ask

Q1Which airplanes are required to meet the lightning protection standards in Part 23?

Per FAR 23.2515, any Part 23 airplane approved for IFR operations must meet these lightning protection requirements unless the applicant shows that exposure to lightning is unlikely.

Q2How does the lightning protection standard differ between safety-critical and capability-critical systems?

Under FAR 23.2515(a), systems whose failure would prevent continued safe flight and landing must continue functioning during and after a strike and recover normally; under 23.2515(b), systems whose failure would only significantly reduce capability just need to recover normal operation in a timely manner after the strike.

Q3Is there any exception to the lightning protection requirement for IFR-certified Part 23 airplanes?

Yes — FAR 23.2515 allows an exception if the applicant can demonstrate that exposure to lightning is unlikely for that airplane.

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Related Sections in Part 23

§ 23.1457

Cockpit Voice Recorders