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In the matter of the petition of Desert Aerospace, LLC for exemption from certain portions of § 

61.58 of Title 14, Code of Federal Regulations (Exemption No. 10779 – Docket No. FAA-2012-

0970), dated September 5, 2012.

Petition for reconsideration of denial

We have received a letter of denial, dated May 24, 2013. In accordance with the 14 CFR 

§11.101, we hereby petition FAA for reconsideration of this denial based on the following:

1. We have additional significant facts, which were not presented in the original petition for 

exemption. Some of these facts are the result of modifications to the systems of the 

aircraft in question, which were accomplished after the initiation of the original petition. 

These modifications further simplify the operation of the aircraft, and may address 

certain concerns FAA noted in the denial letter. Some facts were not presented due to the 

unclear wording of the rule, and are being presented below in response to FAA 

statements in the denial letter.

2. FAA made important factual errors in the denial of our petition. FAA’s use of general 

references, such as “the petitioner’s website”, without citing the specific concerns 

regarding the differences between the operation of this aircraft and other similar aircraft, 

or similarities to turbojet powered aircraft, are ambiguous. FAA’s use of a circular 

reference argument is questionable. 

3. FAA did not correctly interpret the intent of the rule. While the actual deliberative 

process will probably never be disclosed, the denial letter states that it was always FAA’s 

intention to include gliders in the rule. Based on the reasoning presented in the denial 

letter, we believe that FAA’s reasons for denial demonstrate an incorrect interpretation of 

the intent of the rule.

FAA summary of petition request

FAA’s summary of our initial petition for exemption and initial support information is 

essentially correct. FAA’s summary of comments is essentially correct.

FAA’s analysis

General

FAA’s statements regarding the registration number, serial number, operation, general 

description of the aircraft in question (hereinafter referred to as the TST-14) as a ‘turbo-jet 

powered motorglider’ and definition of a glider, per 14 CFR § 1.1, are essentially correct.

Recognition of application of § 61.58 to gliders

FAA notes that “even though this glider does not depend principally on an engine for free flight, 

it remains a turbo-jet powered aircraft”. We recognize that that the TST-14 is a turbo-jet 

powered aircraft, and thus is subject to 61.58, or else there would be no need to petition for an 

exemption.

Methods of compliance with § 61.58

FAA states that “§ 61.58(d)(5) provides a number of ways for a pilot-in-command to accomplish 

a proficiency check”. However, we note that most pilots who have flown, or will fly, this 

aircraft do not fly other turbo-jet aircraft, and may not even hold an airplane rating. For the vast

majority of pilots who will fly the TST-14, the proficiency check will be conducted in this 
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aircraft, IAW § 61.58(d)(5)(i). We also note that, as of this writing, only one person (an FAA 

inspector) has been approved by FAA to provide proficiency checks in the TST-14.

FAA states that “§ 61.58(e) provides an exception ... by only requiring compliance when 

carriage of persons is involved”. We also recognize that the requirement for yearly proficiency

check only applies to pilots who intend to carry passengers. However, we do not recognize that 

this fact has any bearing on this petition. We did not incur the additional expense of a two seat 

aircraft with the intention of flying with one seat empty. To the extent allowed for experimental 

aircraft, the second seat is an asset we intend to utilize. FAA’s implication that we should avoid 

the burden of § 61.58 by simply not utilizing the second seat is outrageous.

Rule wording (Airplane vs. aircraft)

FAA disagrees with our original statements regarding the use of the word ‘airplane’ vs. ‘aircraft’. 

(Note that our position on this was modified in January, 2013 via the FAA docket website.) 

FAA admits that the word ’airplane’ was used in the “Summary Table” and “Description of 

Proposed Changes” sections of the NPRM, but states that the word ‘aircraft’ was used in the 

“Proposed Amendment” section and the final rule. FAA implies that the intent throughout the 

process was to include gliders. FAA further implies that since no description of the change from 

‘airplane’ to aircraft’ was written, one should understand that the use of the word ‘airplane’ was 

unintentional. FAA further states that “the exemption process is not an appropriate mechanism 

to petition for rule change”. We remind FAA that they have a legal burden to clearly state the 

scope of any new regulatory action. The use of the word ‘airplane’ (which specifically excludes 

gliders) in the portions of the NPRM that are likely to be read first (Description of Proposed 

Changes & Summary Table), even if the word ‘aircraft’ is used in the official wording later, 

clearly constitutes a violation of that burden, and creates a situation whereby a reasonable person 

could draw the wrong conclusion as to the scope of the proposed rule. We disagree that the 

wording was corrected in the final rule. While the text of the final rule does use the word 

‘aircraft’; the final rule summary table, as published in the Federal Register (Vol. 76, No. 169 / 

Wednesday, August 31, 2011 / Rules and Regulations, p54096) still uses the word ‘airplane’. 

Despite FAA’s inference that gliders were intentionally included, we seriously doubt that anyone 

involved in this rulemaking ever considered the impact of this rule on turbine powered gliders, 

and we invite FAA to provide records of any deliberative process where turbo-jet powered 

gliders were considered. This being said, we agree that the wording discrepancy involves a rule 

change, and therefore should be taken up in a forum other than the exemption process.

Propulsion type, performance characteristics

FAA states that “the requirement for pilots...to comply with § 61.58 is not dependent on the 

performance of a particular aircraft, or similarities to piston-powered aircraft”. In direct 

contradiction of this statement, FAA goes on to cite the discussion of the final rule, which states, 

in part “pilots...must receive annual proficiency checks to ensure their continued understanding 

of the unique operating characteristics common to turbo-jet powered aircraft”. While we cannot 

dispute that the rule, as written, does not take non-turbine-like performance into account, we 

maintain that this lack of recognition of a special circumstance is the sole reason for this petition 

for exemption. FAA’s argument that ‘an exemption to a rule is not possible because of the rule’ 

is a circular reference argument that in essence undermines the entire exemption process. We 

also point out that FAA does recognize relaxed standards for turbo-jet aircraft which have 
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performance more closely resembling conventional piston-powered aircraft (and vice versa). AC 

23.1309-1E, (15)(g) states:

“... in part 23, turbine-engine airplanes traditionally have been subject to more stringent 

requirements than a single-engine reciprocating airplane. A single-engine reciprocating 

airplane generally has a wider stall-cruise speed ratio than traditional turbine-engine 

airplanes. Such an airplane with a stall speed under 61 knots with simple systems, and 

with otherwise similar characteristics to a traditional single-engine reciprocating 

airplane (except for a higher cruise speed and a more reliable engine that is simpler 

to operate), can be treated as a Class I airplane under this analysis. Conversely, if a 

single-engine reciprocating airplane has the performance, mission capability, and system 

complexity of a higher class (such as cabin pressurization, high cruise altitude, and 

extended range), then that type of airplane design may align itself with the safety 

requirements of a higher class (for example, Class II airplane). These determinations 

should be made during the development of the certification basis.” (Emphasis ours)

We also disagree that the TST-14 possesses any “unique operating characteristics common to 

turbo-jet powered aircraft”, and no characteristics that are complex or which require skills that 

need to be monitored annually.

FAA further rationalizes the denial, citing “significant differences in performance and 

capabilities of turbojet powered aircraft (including gliders) when compared to that of similar 

piston-powered aircraft”. FAA further states, ambiguously, that “the petitioner’s website 

discusses significant differences inherent to the turbo-jet powered TST-14”. We strongly 

disagree that such significant differences exist to the extent that they would need to be monitored 

annually. Also, please note that websites used for sales purposes will contain superlatives. Does 

the Cessna 182 website not make claims of superior performance to other similar aircraft? A 

search of our website (www.desertaerospace.com) for such statements produced the following:

1. “The [TST-14’s] climb far exceeds any other motorglider we have compared with 

(Stemme, DG-505, ASH-26E).” 

2. “Two switches control all engine extend/retract/start functions. They are simply 'Pylon' 

(up/down) and 'Engine' (run/stop). Door actuation is handled automatically by a 

door/pylon sequencer when pylon commands are actuated.”

3. “A cooldown period of about 2 minutes is required after shutdown before retracting the 

engine. Engine retract may be commanded at any time after engine shutdown. The 

pylon/door sequencer will automatically take care of cooldown timing.”

4. “The jet engine is extremely simple, and at 42 pounds, it is only about 1/3 the weight of 

equivalent piston engines.”

5. “It [the turbojet engine] does not require any belt drives, speed reducers or massive 

pylons. It requires very little input from the pilot for starting, and does not require any

prop positioning or 'bumping' for retraction.”

6. “When extended, the jet engine has about the same drag as a single Cessna 172 wheel 

pant.”

7. “The jet engine also produces almost no vibration, eliminating the most significant cause 

of cracking and fatigue failures in all aircraft systems, including the structure and 

avionics.”
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8. “Also looming on the horizon is the elimination of 100LL (leaded) avgas. The BonusJet 

uses jet fuel, which does not contain lead.”

9. “It has a much higher cruise speed than most other motorgliders, allowing it to reach 

good soaring conditions a fair distance from the takeoff point.”

10. “We routinely launch mid-field with two persons while some other motorgliders are 

waiting for a tow, unable to self-launch in the hot & high conditions. The BonusJet's 

takeoff requirements are considerably better than any other motorglider we have 

compared with (Stemme, DG-505, ASH-26E).

We challenge FAA to state specifically which of the statements above, is a “unique operating 

characteristic common to turbojet powered aircraft” that justifies an annual proficiency check. Is 

it the exceptional climb rate, which being significantly better than most motorgliders, provides a 

safe altitude margin during climb, while most other motorgliders are still dodging telephone 

poles 1⁄2 mile off the end of the runway? Is it the two switches that control all engine and pylon 

functions, as opposed to the manual doors, propeller stops, manual door locks, propeller position 

‘bumping’, chokes, primers and compression releases found on most motorgliders? Is it the 

automatic cooldown cycle, instead of the typical manual cooldown that requires partial retraction 

of the engine first? Is it the turbine engine’s light weight and simplicity? Is it the turbine

engine’s low drag when extended? Does handling jet fuel require special skills compared with 

100LL or the auto fuel/oil mix required for two cycle engines?

Recognizing that many pilots who may wish to fly the TST-14 may not be airplane pilots, and 

therefore not familiar with any engine systems, we created a cockpit procedures trainer (CPT), 

which we use for familiarizing new pilots with the cockpit controls. A version of the CPT may

be accessed from our website. This tool was designed for use with instructor supervision, and 

contains some highly exaggerated warnings and errors. For example, leaving the master switch 

on for 20 seconds with no commands will trigger the ‘dead battery’ warning. Holding the engine 

retract over-ride switch with a hot engine will produce a ‘fire’ warning. Maintaining the throttle 

at 100% for 20 seconds produces a ‘flameout’ warning. None of these will happen in reality, but 

the visual cues will remind students of the proper use of controls and best practices with our

aircraft and engine. (Note: The recent addition of a more capable auxiliary fuel pump has 

eliminated the need to reduce throttle after initial climb.)

Again, we challenge FAA to state specifically which of these items is a “unique operating 

characteristic common to turbojet powered aircraft”, which justifies an annual proficiency check. 

The two switches that control all engine and pylon functions? The simple automatic start 

sequence? The automatic door sequencing?

The CPT also includes an instrument panel tour. A review of the instrument panel shows mostly

common glider instruments, such as altimeter, ASI, variometer (sensitive rate of climb indicator

used for soaring), radio, digital fuel quantity, volts, Hobbs and a mirror (allows the pilot to see 

the engine and door position). The digital engine display features LED scales for engine RPM &

EGT, and (idiot light) indictors for generator and oil pressure. A single indicator lamp provides 

pylon status (off = down, on = up, fast blink = in motion and slow (tick tock) blink = retract 

commanded, cool-down timer active).
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Once again, we challenge FAA to state specifically which of these items is a “unique operating 

characteristic common to turbojet powered aircraft”, which justifies an annual proficiency check. 

The mirror, perhaps?

The operating speeds of the TST-14 closely mimic other motorgliders. Its best climb and 

approach speed of 65 knots is consistent with other motorgliders. Its Vne speed of 115 knots is 

similar to other gliders. Its flight controls are identical to those of other motorgliders. It has 

fixed gear, no flaps and no hydraulic systems.

Once again, we challenge FAA to state specifically which of these items is a “unique operating 

characteristic common to turbojet powered aircraft”, which justifies an annual proficiency check. 

The 65 knot best climb speed? The 115 knot Vne? Most jets will not even lift the nose wheel at 

these speeds. Is it the lack of retractable gear, flaps and hydraulics?

FAA states that “FAA data indicates that only three airmen currently hold an experimental 

aircraft authorization to act as pilot in command of the TST-14. The petitioner has not 

demonstrated how the perceived “training burden” on these pilots will benefit the public”. While 

it is true that as of this writing, only three persons are checked out in the TST-14, we disagree 

with FAA’s logic as it applies to safety as a benefit to the public. It is not relief from the 

additional burden on the three current pilots that benefits the public. It is the potential future 

users of this technology who will benefit.

The safety record of piston-powered motorgliders is far from stellar. The complexity of their 

engine systems, coupled with the general lack of reliability of two-cycle engines (originally

manufactured for yard work) and the high drag of the extended engine/propeller combination, 

has resulted in numerous accidents. In stark contrast, the few turbine motorgliders currently

flying with modern turbine engines have a perfect safety record. We believe that equipping 

gliders with modern, aircraft-quality turbine engines represents a vast improvement in safety for 

glider pilots. Since most recreational glider pilots are not professional pilots, and therefore tend 

to balk at additional FAA checkrides, the additional regulatory burden (our use of the term 

‘training burden’ in the original exemption was incorrect) does tend to drive them away from the 

turbine glider concept. We have had numerous calls from pilots interested in flying (or buying) 

the TST-14, who decline when they learn that the TST-14 requires an annual FAA checkride. 

Relief from this regulatory burden, which can involve substantial time and coordination with the 

single FAA inspector allowed to perform this function, would encourage more pilots to examine 

the turbine glider concept, thus not just maintaining an equivalent level of safety, but actually

improving the safety of the sport.

TST-14 Training Requirements

The TST-14’s operating limitations do require an experimental aircraft authorization to act as 

pilot in command. We hold a Letter of Deviation Authority (LODA) to provide transition 

training. Under the terms of the LODA, FAA recognizes our training syllabus. So, anyone who 

acts as PIC in the TST-14 will have additional FAA approved training to account for any

perceived ‘differences’ of this aircraft to other motorgliders. Currently, only one person (an 

FAA inspector) has been authorized to conduct the checkride for this authorization. 
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Summary

FAA has, in essence, based their denial of our petition for exemption on four claims, as follows:

1. The TST-14 has “unique operating characteristics common to turbo-jet powered aircraft”

2. The TST-14 is significantly different from traditional piston powered motorgliders in that 

it possesses “significant differences in performance and capabilities of turbojet powered 

aircraft (including gliders) when compared to that of similar piston-powered aircraft”.

3. “§ 61.58 applies to all turbojet aircraft (including gliders)

4. Due to the low number of pilots currently approved to fly the TST-14, the exemption, if 

granted, provides no benefit to the public

FAA has failed to provide specific examples in support of (1) and (2) above, only ambiguous 

references to “the petitioner’s website”. The TST-14’s low operating speeds and simple systems 

are similar to, or simpler than, those found on most other motorgliders, and are not in any way 

similar to most other turbojet powered aircraft.

FAA’s reasoning that an exemption to a particular rule cannot be granted because of that rule (3) 

is a ridiculous use of a circular reference argument, which, if true, undermines the intent of the 

exemption process. The exemption process exists to recognize specific cases for which the rule, 

though technically applicable, may not be appropriate. We believe the application of certain 

portions of § 61.58 to the TST-14 represent such a case.

FAA’s argument that the low number of pilots currently rated to act as PIC of the TST-14 means 

there is no benefit to the public is not valid. The potential benefit of a simpler, more reliable 

method of launching gliders will benefit the entire soaring community. Any emerging 

technology that improves safety, and which has the potential to cross over to other small aircraft 

segments, represents a benefit to the public as a whole. Modern, small turbine engines are just 

such a technology.

I think it is safe to say that historically, few single items have contributed more to the safety of a 

particular segment of aviation (airlines, helicopters, business aircraft) more than the introduction 

of reliable, vibration-free turbine engines. In the past, there has always been a trade-off between 

the safety and reliability of turbine engines and the high speeds, high altitudes and complex 

systems required for such operations. This is no longer true. Small, reliable turbine engines can 

now operate at essentially the same speeds, altitudes and operating conditions as piston engines, 

with considerably simpler systems. Nowhere is this more easily demonstrated than in the sport 

of soaring, where launching by means of a rope or tiny two-cycle engine has always been one of 

the most critical (and dangerous) parts of the flight. The introduction of turbine engines to 

gliders will save lives! Any regulatory burden that hinders the widespread acceptance of 

modern, aircraft quality turbine engines in gliders will only serve to perpetuate these antiquated 

launch methods.

In light of FAA’s failure to provide evidence of operational characteristics common to turbojet 

powered aircraft, or differences to conventional motorgliders, we hereby request the FAA 

reverse the denial decision. May common sense prevail...