Regulatory

Experimental by Design, Regulated by Law: Who can Maintain an LSA?

TBX Team

Regulatory

Experimental by Design, Regulated by Law: Who can Maintain an LSA?

TBX Team

As we saw last week in our experimental aircraft counts posting, experimental aircraft are a huge part of the General Aviation fleet: over 30,000 registered experimental aircraft (including 28k homebuilts) keep an active N-Number registration. With respect to maintenance, however, there continues to be confusion as to who can do what on an experimental aircraft.

Although Part 43 does not apply to experimental category aircraft [as per 43.1(b)], Part 91 still applies. This includes, but is not limited to: log entries (91.417); ATC Transponder checks (91.413); altimeter pitot system checks (91.411); ELT battery checks (91.207); AROW (pre-flight documents); W&B limitations, VOR checks for IMC, etc., and more. See our FARs Cheatsheet for a rundown on 43 vs 91.

To help summarize Experimental maintenance, we created the following table across E-AB, E-LSA, S-LSA, and certificated. As you can see - there is no "one size fits all" regarding Experimental maintenance.

	E-AB	E-LSA	S-LSA	Certificated
Key FARs	21.191 / AC 20-27	21.191	21.190 / 91.327	Part 43, 91
Build Category	51% Rule	No 51% rule	"Ready to Fly"	TC/PC
Build Deviations?	Yes	None (until after cert)	Mnfr Options	STCs / Field Approvals
Condition Inspection / Annual	Only the Builder (with a Repairman Certificate - no class req); or A&P/CRS	Min LSRMI (16 hours); or A&P/CRS	Min LSRM (120 hours) or A&P - see Mnfr Mx Manual for guidance; or CRS	IA Signoff; Scope in Part 43, Appendix D; or CRS
What Mods can I do?	Any	Need Mnfr Permission prior to Airworthiness Certificate; Any post-certificate	Mnfr must approve all changes (LOA)	STC, Field Approval, or Alteration (Form 337); IA/A&P
Mx, Repairs, Mods - who can do them?	Anybody	Anybody	Min LSRM (120 hours) or A&P - see Mnfr Mx Manual for guidance	A&P and/or IA; Owners limited to Prev Mx as per Part 43, Appendix A.(c)
Who can sign off ?	No sign off required until condition insp; Part 91.417 log still required	No sign off required until condition insp; 91.417 log still required	Min LSRM (120 hours) or A&P - see Mnfr Mx Manual for guidance;	A&P/IA/CRS
Next Owner?	You can do the work and the logs, but sign off is from Original builder, A&P, or CRS	Can take the LSRMI (16 hours)	Min LSRM (120 hours) or A&P - see Mnfr Mx Manual for guidance	A&P/IA/CRS
Mandatory SBs	No, unless incorporated into an AD	No, unless incorporated into an AD	Yes, Compliance is Mandatory	Only legally required under Parts 121 / 135
Night or IFR?	Yes, if allowed by AOI and properly equipped	Yes if allowed by AOI and properly equipped	Yes, if allowed by AOI and properly equipped	Yes, if properly equipped (and if pilot is IR for IFR)
IMC Conditions?	Yes, if IFR rated + airplane equipped (and the pilot is IR)	Yes, if IFR rated + airplane equipped (and the pilot is IR)	Yes, if IFR rated + airplane equipped (and the pilot is IR)	Yes, if IFR rated + airplane equipped

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One area of confusion within the Experimental world is AD compliance. Many of the "newer" ADs will say something akin to "this AD applies to all airplanes certificated in any category." When you see that—it doesn't matter what type of aircraft you have—you need to comply. However, with some of the "older" ADs, this key phrase may be missing.

Even so, we're not off the hook. Referring back to the (legal) definition of "Airworthy" (Part 3.5), the aircraft not only conforms to its type design but is in a condition for safe operation. Not complying with a known AD or safety issue is in direct conflict with Part 3.5. Note: How that compliance is achieved, however, gives the experimental holder more degrees of latitude than certificated aircraft.

Of course, not complying with known safety issues from the OEM (either informative or mandatory) may pose an additional risk if there's a future incident (more on this here).

One of the biggest misconceptions we've run into within "Experimental Land" is that you have to have your Repairman Certificate to do maintenance on an experimental aircraft. That is not the case. ANYONE can do maintenance and/or modifications on an E-LSA / E-AB aircraft; however, you need a minimum of a Repairman Certificate for the annual "condition inspection".

The S-LSA category acts the most similar to certificated aircraft, going so far as to require 337s as Part 43 for major repairs and alterations on TC’d products (see AC 65-32A). For those who are curious, a sample condition inspection can be found at the back of AC 90-89C (page 116).

As proponents of safety, if there are ways that we can help the Experimental community imrpove maintenance and compliance, please let us know.

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