Jean-Pierre Harrison Page 1 of 5 

11835 Skyline Blvd. r .^-r, .pMT np 

I^atos,CA95033 '-^siwiO N 

408/872-1257 ' " ^ ' "" ' 6July2011 

.•i!! JJL ! ! A > 08 

Petition to Apply FAR §91.119(d) Minimum Sqfe AMtudes: General: HeUcapters 

to all Rotorcraft 

Introduction 

This document is a refiling of my earlier petition Docket FAA-2009-0838 which was denied by the 

Federal Aviation Administration on 15 December 2010. Said denial was based on grossly incorrect 

application and/or interpretation of the relevant Federal Aviation Regulations, lack of fundamental 

understanding of the operation of rotary-wing aircraft, and an obvious prejudice against gyroplanes as a 

class of aircraft. This refiled petition is updated to account for the changes to FAR 91.119: Minimum Safe 

Altitudes: General which came into effect after this petition was filed and were applicable eight months 

before the date of the denial of my original petition. Copies of my original petition, the Federal Aviation 

Administration denial letter, and my response to same are included as supporting doamientation to this 

refiled petition. 

Explanation of Proposed Action and Its Purpose 

There have historically been three fimdamental types of rotorcraft: gyrodyne, gyroplane, and helicopter, 

of which the latter two have been continually in service since their inception. Certification and operational 

regulations for helicopters have been developed and refined since its emeigence as a practical aircraft and 

currentiy reflect the capabilities and limitations of this class of aircraft. The same is not true for the 

gyroplanes the operation of which are sometimes governed by helicopter regulations and sometimes by 

airplane regulations. 

Gyroplanes have by and large been historically regarded as testbeds for rotary-wing development. 

Successive models of gyroplanes manufactured by licensees of the Cierva Autogiro Company, Ltd. 

(Autogiro Company of America, etc.) each furthered the development of the rotary wing, witii the result 

that the technology never matured until about the late 1930s. This rotary-wing technology was used in the 

first successful helicopters such as tiie Sikorsky VS-300, Sikorsky R-4, Bell 47, Kaman K-225, etc. 

Helicopter development thereafter displaced fUrther gyroplane efforts with the exception of three FAA 

certificated examples of the latter (Air & Space 18 — FAA Type Certificate 1H17, Avian 2-180 — FAA 

Type Certificate H5EA, McCuIloch J-2 — FAA Type Certificate H6WE) to the present. This lack of 

attention has resulted in the Federal Aviation Regulations becoming out of date with regard to gyroplane 

capabilities. 

The purpose of this petition is to apply FAR §91.119(d) Minimum Safe Altitudes: General to all aircraft 

classes within the rotorcraft category, i.e. gyrodyne, gyroplane, and helicopter, for the following reasons. 

1 Apply consistent regulations to all aircraft classes within the rotorcraft category when those aircraft 

possess common capabilities. 

2 Remove limitations from gyroplane operations which restrict the usefulness of this class of aircraft 

without providing any increase in safety. 

3 Recognition of the resurgence of interest in and development of gyroplanes. At the time of writing, 

there are two well-funded, professionally managed gyroplane development efforts (CarterCopters, 
Jean-Pierre Harrison Page 2 of 5 

11835 Skyline Blvd. 

Los Gatos,CA 95033 

USA 

408/872-1257 6 July 2011 

www.cartercopters.com and Groen Brothers Aircraft, www.groenbros.com in addition to those 

developed under the Light Sport Aircraft Category (LSA) certification regulations. 

4 The resurgence of interest in gyroplanes was recognized by the FAA by its inclusion of a dedicated 

section on gyroplanes, comprising eight chapters, in the 2000 edition of Rotorcraft Flying Handbook, 

FAA-H-8083-21, for the first time in several decades. 

Proposed Language for Redefinition of FAR §91.119(d) Mimmum St^eAMtudes: General 

d) Rotorcraft. Rotorcraft may be operated at less than the minimums prescribed in paragraph (b) or 

(c) of this section if the operation is conducted without hazard to persons or property on the 

surface. In addition, each person operating a rotorcraft shall comply with any routes or altitudes 

specifically prescribed for rotorcraft by the Administrator. 

The term rotorcraft replaces the original tenn helicopter in the preceding. 

Public Interest Served by the Proposed Action 

The public interest served by the proposed action is consistent regulation of all aircraft classes within the 

rotorcraft category by eliminating unnecessary altitude limitations while maintaining safety at least at 

current levels. 

The purpose of the existing regulation, FAR §91.119(d) Minimum Safe Altitudes: General, is to permit 

helicopter operations at any altitude providing hazardous situations are avoided and a safe autorotative 

landing can be executed in the event of engine failure. 

Following an engine failure in a helicopter, its rotor must transition from propulsive state to autorotative 

state, and the ensuing landing is always an emergency procedure. The pilot must manually establish and 

maintain rotor RPM with collective pitch control while simultaneously establishing and maintaining the 

required glide airspeed (which also governs rotor RPM) with the cycUc pitch control. Helicopters may 

execute an autorotative emergency landing with either a collective flare or a cyclic flare. Landing from a 

collective flare is the less common of the two types of emergency landings since these require a 

favourable combination of wind, density altitude, high rotor inertia, rotor RPM, aircraft gross weight, and 

pilot technique for the successful outcome of the procedure. Most emergency landings from an 

autorotative descent are executed with a cycUc flare since the aforementioned favourable conditions are 

not always reliably present. A cyclic flare inevitably results in a run-on landing during which the 

helicopter — particularly those with skid landing gear — is highly prone to rollover. In either case, these 

landings are an emergency condition for which a helicopter is designed to provide adequate, thou^ far 

from optimal, performance. 

A gyroplane is equally capable of safe operation at low altitudes, but since its rotor is always in 

autorotation, landing after engine failure is a normal procedure. The main concem for the pilot is to 

establish and maintain the required glide airspeed; management of rotor RPM is not a consideration. 

Touchdown may be followed by a landing run, but is usually of minimal, if any, length, again depending 
Jean-Pierre Harrison Page 3 of 5 

11835 Skyline Blvd. 

Los Gatos,CA 95033 

USA 

408/872-1257 6 July 2011 

on airspeed at touchdown, weight, density altitude, wind, and pilot technique. 

Gyroplanes may be fitted with collective pilch control (Avian 2-180) or a collective pitch trim (Air & 

Space 18A). In the case of the former, a collective flare to a landing from an autorotative descent is a 

normal procedure for which the gyroplane is designed. The collective pitch trim fitted to the Air & Space 

18A does not act quickly enough to enable a landing from a collective flare. Gyroplanes in general are 

landed from a cyclic flare, which due to the low rotor disk loading necessary to provide adequate 

performance, is followed by minimal — if any — ground roll usually no longer than the length of the 

aircraft. Experience shows conclusively that a current FAA certificated gyroplane pilot flying an FAA 

Standard Airworthiness Category gyroplane — the intended beneficiary of this petition — can execute a 

no-roll landing from a cyclic flare as a normal procedure. For example, an Air & Space 18A can easily 

operate to and from a helipad — and has done so many times as a matter of normal procedure. Any 

ground roll after touchdown is also a noimal procedure since a gyroplane is designed to operate at speed 

on its landing gear when executing a rolling takeoff. 

It is seen that following an engine failure, a gyroplane operates normally with the added advantage of 

requiring less area for a safe, minimum ground roll landing than an comparable helicopter which must be 

established in stable autorotation before touching down and usually requiring a ground run to complete 

the landing procedure. 

In summary, the gyroplane offers equal or better levels of safety following an engine failure than does a 

comparable helicopter. 

Supporting Information 

Height-Velocity Limitations 

In both gyroplanes and helicopters, the pilot must avoid violating the height-velocity limitations specified 

in the Approved Flight Manual. Height-velocity limitations are less restrictive for gyroplanes compared to 

helicopters as can be seen from the examples included in Height-Velocity Graph appendices. 

Gyroplane height-velocity charts have one avoid region; heUcopter height velocity charts have two avoid 

regions. The high altitude/low airspeed avoid region is common to both gyroplane and helicopter. Its 

purpose is to inform the pilot of the combination of altitude/airspeed from which it is not possible to land 

the aircraft without hazard followmg engine failure. In the gyroplane case, the main hazard is a hard 

landing due to excessive descent rate and insufficient airspeed to trade for increased rotor thrust in a 

cyclic flare; in the helicopter case, the hazard is complete loss of control on landing due to inability to 

establish stable autorotation and stabilize the descent rate. In the case where a helicopter is established in 

a stable autorotative descent, flight through the avoid region of the height-velocity chart will also result in 

damage to the aircraft on landing for the same reasons affecting a gyroplane. A helicopter in an 

autorotative descent is nothing more than an gyroplane rendered inefiicient because of high disk loading, 

negative rotor blade twist, and power losses arising from the tail rotor drive system. 
Jean-Pierre Harrison Page 4 of 5 

11835 Skyline Blvd. 

Los Gatos,CA 95033 

USA 

408/872-1257 6 July 2011 

The lower altitude/high airspeed avoid region applies only to helicopters. Engine failure at low 

altitude/high airspeed provides the pilot insufficient time to establish stable autorotation before the 

helicopter contacts the ground. In addition, the high aircraft pitch angle required to decelerate the 

helicopter for landing easily results in the tail rotor striking tiie ground. Either of these factors easily 

results in loss of control of the helicopter during touchdown. 

At 100 feet AGL, Air & Space 18A must maintain a minimum airspeed of 36 mph, and the Enstrom F-28 

a minimum airspeed of 30 mph to remain outside their respective height-velocity graph avoid regions. At 

300 feet AGL, both Air & Space 18A and Enstrom F-28 both have a minimum airspeed of 0 mph to 

remain outside theu" respective avoid regions. In contrast to the Enstrom F-28, the Air & Space 18A can 

operate safely, indefinitely, at altitudes below 50 ft at a minimum airspeed of 45 mph. 

Descent Rates During Engine-Out Autorotation 

Since a gyroplane rotor is designed to fly at all times in autorotative state, it is generally designed to be as 

efficient as possible in this flight condition. Conversely, a helicopter rotor is designed to fly in propulsive 

state under normal conditions, with autorotative state being the emergency case. It follows that a 

helicopter rotor is designed primarily for efficiency during propulsive state, with only minimum 

efficiency as necessary being provided for operation in autorotative state. The end result is that after an 

engine failure, the gyroplane rotor is operating under normal conditions, and the helicopter rotor is 

operating under emergency conditions. The resulting descent rate for a gyroplane is approximately onethird that of a comparable helicopter as can be seen below. 

The followmg table presents a list of gyroplanes that have received Approved Type Certificates from the 

FAA or its predecessor, the CAA. As can be seen, the Pitcaim PA-24 had lowest disk loading of 1.39 

Ib/ft^ and tiie McCulloch J-2 the highest disk loading at 3.00 Ib/ft^ It must be noted tiiat tiie McCulloch J2 disk loading value is anomalous in that it is the sole example exceeding the next highest disk loading 

value of 2.05 lb/ft=* for tiie Pitcaim PA-19, and that by a 50% margin. In general, a disk loading of 2.00 

Ib/ft^ has been established as an upper limit for good performance in gyroplanes; performance of the 

McCulloch J-2 was very poor as can be readily verified from its Approved Flight Manual. Nevertheless, a 

pilot can routinely execute a no-roll landing in the McCulloch J-2. 

The average disk loading for all gyroplanes listed below is 1.89 Ib/ft^. 

The average disk loading for all gyroplanes listed below except the McCulloch J-2 is 1.80 Ib/ft^. 
Jean-Pierre Harrison 

11835 Skylme Blvd. 

Los Gatos, CA 95033 

USA 

408/872-1257 

Gyroplane Make/Model 

Pitcaim-Cierva PCA-2 

Pitcaim-Cierva PCA-3 

Pitcaim PAA-l/PA-20 

Pitcaim PA-18 

PitcauTi PA-19 

Pitcaim PA-24 

Kellett K-2 

KellettIC-3 

Kellett KD-1 

Kellett KD-IA 

Kellett KD-IB 

Air & Space 18A 

McCulloch J-2 

Avian 2-180 

Page 5 of5 

6 July 2011 

ATC/FAA Type Certiiicate 

Number 

410 

446 

433 

478 

509 

507 

437 

471 

712 

712 

712 

1H17 

H6WE 

H5EA 

Disk 

1.89 

1.93 

1.65 

1.51 

2.05 

1.39 

1.72 

1.82 

1.79 

1.91 

1.91 

1.87 

3.00 

1.99 

Disk Loading lb/ft' 

Autorotative performance of a rotorcraft is dependent primarily on disk loading and blade inertia. The 

average disk loading for helicopters is 5~10 Ib/ft^ which results in descent rates at best glide airspeed 

ranging from approximately 1,800-3,600 FPM (Leishman, p.43,62). For the gyroplane disk loadings of 

1.39-3.00 Ib/ft^, the corresponding descent rates are approximately 500-1,100 FPM. For the average 

gyroplane disk loading of 1.89 Ib/ft^, the corresponding descent rate is approximately 700 FPM. 

Appendices 

1. Air & Space 18A gyroplane height-velocity graph. 

2. McCulloch J-2 gyroplane height-velocity graph. 

3. Enstrom F-28 helicopter height-velocity graph. 

4. Robinson R-22 helicopter height-velocity graph. 

5. Petition Docket FAA-2009-0838. 

6. FAA denial letter to petition Docket FAA-2009-0838. 

7. Petitioner response to FAA denial letter to petition Docket FAA-2009-0838. 

References 

Leishman, J. Gordon. Principles of Helicopter Aerodynamics, New York. Cambridge University Press, 

2000. 

Jean-Pierre Harrison 
EHEIGHT VS. vSLOCltY: 

•=rl":^g^F= 

Air & Space 18A Height-Velocity Graph 
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ROBINSON 

MOE^LR22 

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FAA APPROVEO 7 AUGUST 1985 5 ^ 

Robinson R-22 Height-Velocity Graph 
Jean-Pierre Harrison Page I of 8 

4107 Elderwood 

Seabrook, TX 77586 

281/326-1188 

jp(a selec.net 

Petition to Apply FAR §91.119(d) Minimum Safe Altitudes: General: Helicopters to all Rotorcraft 

Explanation of Proposed Action and Its Purpose 

There have historically been three fundamental types of rotorcraft, gyrodyne, gyroplane, and helicopter, of which the latter 

two have been continually in service since their inception. Certification and operational regulations for helicopters have been 

developed and refined since its emergence as a practical aircraft and currently reflect the capabilities and limitations of this 

class of aircraft. The same is not true for the gyroplanes the op>eration of which are sometimes governed by helicopter 

regulations and sometimes by Mrplane regulations. 

Gyroplanes have by and large been historically regarded as testbeds for rotary-wing development. Successive models of 

gyroplanes manufactured by Licensees of the Cierva Autogiro Company, Ltd. (Autogiro Company of America, etc.) each 

furthered the development of the rotary wing, with the result that the technology never matured until about the mid 1930s. 

This rotary-wing technology was used in the first successful helicopters such as the Sikorsky VS-300, Sikorsky R-4, Bell 47, 

Kaman K-225, etc. Helicopter development thereafter displaced further gyroplane efforts with the exception of three FAA 

certificated examples of the latter (Air & Space 18A, Avian 2-180, McCulloch J-2) to the current time. This lack of attention 

has resulted in the Federal Aviation Regulations becoming out of date with regard to gyroplane capabilities. 

Thepurposeof this petition is to apply FAR §91.119(d) Minimum Safe Altitudes: General \aa\\ aircraft classes within the 

rotorcraft category, i.e. gyrodyne, gyroplane, and helicopter, for the following reasons. 

1 Apply consistent regulations to all aircraft classes within the rotorcraft category when those aircraft possess common 

capabilities. 

2 Remove limitations from gyroplane operations which restrict the usefulness of this class of aircraft without providing any 

increase in safety. 

3 Recognition of the resurgence of interest in and development of gyroplanes. At the time of writing, there are two wellfunded, professionally managed gyroplane development efforts (CarterCopters, www.cartercopters.com and Groen 

Brothers Aircraft, www.groenbros.com in addition to those developed under the Light Sport Aircraft Category (LSA) 

certification regulations. 

Proposed Language for Redeflnition of FAR §91.119(d) Minimum Safe Altitudes: General 

d) Rotorcraft. Rotorcraft may be operated at less than the minimums prescribed in paragraph 

(b) or (c) of this section if the operation is conducted without hazard to persons or 

property on the surface. In addition, each person operating a rotorcraft shall comply with 

any routes or altitudes specifically prescribed for rotorcraft by the Administrator. 

The term rotorcraft replaces the original term helicopter in the preceding. 

Public Interest Served by the Proposed Action 

The public interest served by the proposed action is consistent regulation of all aircraft classes within the rotorcraft category 

by eliminating unnecessary altitude hmitations while maintaining safety at least at current levels. 

Thepurposeof the existing regulation, FAR §91.119(d) Minimum Safe Altitudes: General, is to permit helicopter operadons 

at any altitude providing hazardous situations are avoided and a safe autorotative landing can be executed in the event of 
Jean-Pierre Harrison Page 2 of 8 

4107 Elderwood 

Seabrook, TX 77586 

281/326-1188 

iD@selec.net 

engine failure. 

Following an engine failure in a helicopter, its rotor must transition from propulsive state to autorotative state, and the ensuing 

landing is always an emergency procedure; the pilot must manually estabUsh and maintain rotor RPM while simultaneously 

estabUshing and maintaining the required glide airspeed. Landing is usually followed by a run, the length of which varies 

with airspeed at touchdown, weight, density altitude and wind 

A gyroplane is equally capable of safe operation at low aldtudes, but since its rotor is always in autorotation, landing after 

engine failure is essentially a normal procedure; the main concem for the pilot is to establish and maintain the required gUde 

airspeed; maintenance of rotor RPM is not a consideration. Touchdown may be followed by a landing run, but is usually of 

minimal, if any, length, again depending on airspeed at touchdown, weight, density altitude and wind. 

It is seen that following an engine failure, a gyroplane operates normally with the added advantage of requiring less area for a 

safe, minimum ground roll landing than an comparable heUcopter which must be established in stable autorotation before 

touching down and usually requiring a ground run to complete the landing procedure. 

In summary, the gyroplane offers equal or better levels of safety following an engine failure than does a comparable 

helicopter. 

Supporting Information 

Height-Velocity Limitations 

In both gyroplanes and helicopters, the pilot must avoid violating the height-velocity limitations specified in the Approved 

Flight Manual. Height-velocity limitations are less restrictive for gyroplanes compared to helicopters as can be seen from the 

examples included in Appendix I: Height-Velocity Graphs. 

Gyroplane height-velocity charts have one restricted height-velocity region; helicopter height velocity charts have two 

restricted height-velocity regions. The higher altitude/low airspeed restricted height-velocity region is common to both 

gyroplane and helicopter. Its purpose is to inform the pilot of the combination of altitude/airspeed from which it is not 

possible to land the aircraft without hazard following engine failure. In the gyroplane case, the main hazard is a hard landing 

due to excessive descent rate in the helicopter case, the hazard is complete loss of control on landing due to inability to 

establish stable autorotation and stabilize the descent rate. 

The lower altitude/high airspeed restricted height-velocity region applies only to helicopters. Engine failure at low 

altitude/high airspeed provides the pilot with insufficient time to establish stable autorotation before the helicopter contacts 

the ground. In addition, the high pitch angle required to decelerate the helicopter for landing easily results in the tail rotor 

striking the ground. Either of these factors easily results in loss of control of the helicopter during touchdown. 

At 100 feet AGL, Air & Space 18A must maintain a minimum airspeed of 36 mph, and the Enstrom F-28 a minimum airspeed 

of 30 mph to remain outside their respective restricted height-velocity regions. At 300 feet AGL, both Air & Space ISA and 

Enstrom F-28 both have a minimum airspeed of 0 mph to remain outside their respective restricted height-velocity regions. In 

contrast to the Enstrom F-28, the Air & Space ISA can operate safely, indefinitely, at altitudes below 50 ft at a minimum 

airspeed of 45 mph. 
Jean-Pierre Harrison Page 3 of 8 

4107 Elderwood 

Seabrook. TX 77586 

281/326-1188 

jpta <ialec.net 

Descent Rates During Engine-Out Autorotation 

Since a gyroplane rotor is designed to fly at all times in autorotative state, it is generally designed to be as efficient as 

possible in this flight condition. Conversely, a helicopter rotor is designed to fly in propulsive state under normal conditions, 

with autorotative state being the emergency case. It follows that a helicopter rotor is designed primarily for efficiency during 

propulsive state, with only minimum efficiency as necessary being provided for operation in autorotative state. The end result 

is that after an engine failure, the gyroplane rotor is operating under normal conditions, and the helicopter rotor is operating 

under emergency conditions. The resulting descent rate for a gyroplane is approximately one-third that of a comparable 

helicopter as can be seen below. 

The following table presents a hst of gyroplanes that have received Approved Type Certificates from the FAA or its 

predecessor, the CAA. As can be seen, the Pitcaim PA-24 had lowest disk loading of 1.39 Ib/ft^ and the McCulloch J-2 the 

highest disk loading at 3.00 Ib/ft^. It must be noted that the McCulloch J-2 disk loading value is anomalous in that it is the 

sole example exceeding the next highest disk loading value of 2.05 Ib/ft^ for the Pitcaim PA-19, and that by a 50% margin. In 

general, a disk loading of 2.00 Ib/ft^ has been established as an upper limit for good performance in gyroplanes; performance 

of the McCulloch J-2 was very poor as can readily be verified from its Approved Flight Manual. 

The average disk loading for all gyroplanes listed below is 1.89 Ib/ft^. 

The average disk loading for all gyroplanes listed below except the McCulloch J-2 is 1.80 Ib/ft^. 

Gyroplane Make/Model 

Pitcaim-Cierva PCA-2 

Pitcaim-Cierva PCA-3 

Pitcaim PAA-l/PA-20 

Pitcaim PA-18 

Pitcaim PA-19 

Pitcaim PA-24 

Kellett K-2 

Kellett K-3 

Kellett KD-1 

Kellett KD-1 A 

Kellett KD-IB 

Air & Space ISA 

McCulloch J-2 

Avian 2-180 

ATC/FAA Type Certificate Number 

410 

446 

433 

478 

509 

507 

437 

471 

712 

712 

712 

1H17 

H6WE 

H5EA 

Disk Loading Ib/ft^ 

1.89 

1.93 

1.65 

1.51 

2.05 

1.39 

1.72 

1.82 

1.79 

1.91 

1.91 

1.87 

3.00 

1.99 

Autorotative performance of a rotorcraft is dependent primarily on disk loading and blade inertia. The average disk loading 

for helicopters is 5-10 lb/ft' which results in descent rates at best glide airspeed ranging from approximately 1,800-3,600 

FPM (Leishman, p.43,62). For the gyroplane disk loadings of 1.39-3.00 Ib/ft^, the corresponding descent rates are 

approximately 500-1,100 FPM. For the average gyroplane disk loading of 1.89 Ib/ft^, the corresponding descent rate is 

approximately 700 FPM. 
Jean-Pierre Harrison Page 4 of 8 

4107 Elderwood 

Seabrook, TX 77586 

281/326-1188 

jp@selec.net 

Appendix 1: Height-Velocity Graphs 

1. Air & Space 18A gyroplane 

2. McCulloch J-2 gyroplane 

3. Enstrom F-28 helicopter 

4. Robinson R-22 helicopter 
Q 

U.S. Department 800 Independence Ave., S.W. 

of Transportation Washington, DC 20591 

Federal Aviation 

Administration 

Dec 15 2010 

Mr. Jean-Pierre Harrison 

11835 Skyline Boulevard 

Los Gatos, CA 95033 

Dear Mr. Harrison: 

In your August 29, 2009 letter, you petitioned the Federal Aviation Administration 

(FAA) to amend § 91.119(d) of Title 14, Code of Federal Regulations (14 CFR) by 

changing "helicopter" to "rotorcraft." This change would then include gyroplanes. 

You have made some good points. However, when the FAA responds to petitions for 

rulemaking, it must follow the requirements of 14 CFR part 11, particularly those 

guidelines for processing petitions for rulemaking found in § 11.73. As stated in that 

section, the FAA uses the following criteria when making a decision as to whether or not 

to amend current regulations based on a petition for rulemaking: 

1) the immediacy of the safety or security concerns the petition raises; 

2) the priority of other FAA issues; and 

3) the resources we have available to address these issues. 

Most gyroplanes flown in the United States are registered as "Experimental-Amateur 

Built" or as Light Sport Aircraft (LSA). Only a few are FAA certificated. Since 

§91.319 does not allow experimental aircraft to be operated over a densely populated 

area or in a congested airway, they would not be allowed to operate over a congested area 

at any altitude or exercise the privileges of § 91.119(b) or use helicopter routes which are 

normally considered to be heavily congested airways. 

Helicopters operate at lower altitudes in congested areas to perform aerial work such as: 

news gathering, security surveillance, construction, and transportation from one location 

to another within a congested area without requiring a waiver for each operation. This is 

not applicable to most gyroplanes since experimental aircraft may not be used for 

commercial purposes, and gyroplanes are not able to hover, which is a necessary part of a 

large portion of aerial work for helicopters. 

AFS-09-393-P 
Normally, helicopter pilots are required to have more training and a higher certification 

level than gyroplane pilots since many gyroplanes are operated by LSA pilots while 

helicopter pilots must have at least a private pilot certificate. Accepting the proposed 

change in this rule would have an adverse affect on safety by allowing less skillful pilots 

to fly lower and closer to congested areas. 

The FAA continues to commit resources to develop helicopter routes over and through 

congested areas to channel helicopter traffic along flight paths to avoid the flow of 

airplanes. Safety of these routes could be compromised if the FAA allowed much less 

capable gyroplanes to fly on these routes. 

The FAA finds that the height-velocity (HA^) curve you referenced only applies to take 

offs and level flight with power. It is not appropriate to consider the H/V curve in an 

autorotative landing as a result of a powerplant failure which is the focus of § 91.119. 

Helicopters have the ability to vary their glide path during an autorotative landing to a 

greater degree using collective pitch applications, which can be used to complete an 

autorotative landing with very little or no ground run. Few gyroplanes are equipped with 

controllable collective pitch to use for autorotative landing where these collective pitch 

applications may be used. Since gyroplanes vary in design capabilities, it would not be 

prudent for the FAA to allow all gyroplanes to exercise the same privileges for which 

very few gyroplanes qualify. 

For the reasons above, we are tinable to consider and thereby deny your petition for 

rulemaking in accordance with 14 CFR § 11.73. 

Accordingly, Docket No. FAA-2009-0838 is being closed. 

Sincerely, 

RaymcUid Towles 

Acting Director, Flight Standards 

Service 
Jean-Pierre Harrison 

11835 Skyline Blvd. 

Los Gatos CA 95033 

USA 

408/872-1257 jph@wt.net 

6 July 2011 

Acting Director, Flight Standards Service 

Federal Aviation Administration 

800 Independence Avenue, SW 

Washington, DC 20591 

Dear Sir, 

Thank you for your letter of 15 December 2010 (copy enclosed). Since its receipt I have debated 

whether it is worthwhile to respond to the statements contained therein since they based on a selective 

interpretation of the relevant Federal Aviation Regulations, include unsupportable assertions, and 

disclose a fundamental lack of understanding of rotary-wing aircraft operations. These statements are 

even more disheartening since they originate from the headquarters of the agency responsible for 

promoting and regulating aviation operations in the United States, and one would expect a response to 

any petition to be at least consistent, logical, accurate, and objective. 

Please note that comments in this font originate from Mr. Jon Stark, an interested party to this petition, 

who like myself holds CPL/and CFI gyroplane pilot certificates among other qualifications, and who 

also regularly operates two gyroplanes certificated in the Standard Category by the FAA. Mr. Stark is 

also an attorney. 

My petition (copy enclosed) was restricted to changing FAR 91.119(d) by replacing helicopter with 

rotorcraft, thus extending the waiver of minimum altitude requirements to gyroplanes and gyrodynes. 

To quote therefrom: 

Proposed Language for Redefinition of FAR 91.119(d) Minimum Safe Altitudes: General 

d ) Rotorcraft. Rotorcraft may be operated at less than the minimums prescribed in paragraph (b) 

or (c) of this section if the operation is conducted without hazard to persons or property on the 

surface. In addition, each person operating a rotorcraft shall comply with any routes or altitudes 

specifically prescribed for rotorcraft by the Administrator. 

In lightof the changes to FAR 91.119 arising from the advent of light sport aircraft (LSA) and sport 

pilot certification, said regulation, effective as of 2 April 2010 follows: 
FAR 91.119: Minimum Safe Altitudes: General. 

Except when necessary for takeoff or landing, no person may operate an aircraft below the following 

altitudes: 

a ) Anywhere. An altitude allowing, if a power unit fails, an emergency landing without 

undue hazard to persons or properly on the surface. 

b ) Over congested areas. Over any congested area of a city, town, or settlement, or over any 

open air assembly of persons, an altitude of 1,000 feet above the highest obstacle within a 

horizontal radius of 2,000 feet of the aircraft. 

c ) Over other than congested areas. An altitude of 500 feet above the surface, except over 

open water or sparsely populated areas. In those cases, the aircraft may not be operated closer 

than 500 feet to any person, vessel, vehicle, or structure. 

d ) Helicopters, powered parachutes, and weight-shift-control aircraft. If the operation is 

conducted without hazard to persons or property on the surface1 ) A helicopter may be operated at less than the minimums prescribed in paragraph (b) or 

(c) of this section, provided each person operating the helicopter complies with any routes or 

altitudes specifically prescribed for helicopters by the FAA; and 

2 ) A powered parachute or weight-shift control aircraft may be operated at less than the 

minimums specified in paragraph (c) of this section. 

1 ) 

Your response immediately referred to experimental gyroplanes which due to restrictions of their 

airworthiness certification category are prohibited from operations over congested areas or along a 

congested airway (FAR 91.319(c)). These restrictions apply to all experimental aircraft in any 

category/class, not just gyroplanes. My petition did not request waiver of flight operating limitations for 

experimental rotorcraft as governed by FAR 91.319. Your response conflated the operating limitations 

of two different aircraft certification categories. 

If experimental aircraft are already prohibited from flying over congested areas and airways, 

then granting the petition could not possibly reduce the safety of operation of experimental 

aircraft over those regions, since there will not be any such operations. You contradict 

yourself. 

With respect to your statement regarding the various uses of helicopters in low altitude operations, it is 

a matter of record that gyroplanes have been and are safely and successfully used in news gathering, 

security surveillance, construction, and transportation from one location to another within congested 

areas. 

The ability of helicopters to hover has no relevance to a question of safe altitudes for 

operations. The necessity of hovering is both overstated and not germane. Gyroplanes may 

also be used for news gathering, security surveillance, and transportation, without hovering, 

as well as aehal photography, mapping, and other tasks, and like helicopters, may be 

operated at airspeeds down to zero without risk of low altitude stall/spin incidents. No aircraft 

hovers in an emergency landing. 
Your statement that helicopter pilots are required to have more training and higher certification level 

than gyroplane pilots is a red herring since you follow this by arguing that the petition would allow 

lesser trained gyroplane pilots (presumably sport pilots flying experimental gyroplanes, LSA 

gyroplanes, or certificated gyroplanes that meet LSA rules) to fly lower in congested areas. This 

statement ignores FAR 91.119(d)(2) which explicitly permits powered parachutes or weight-shift control 

aircraft, which are invariably certificated in the experimental or LSA categories operated by sport 

pilots, and which was effective eight months as of the date of your letter of 15 December 2010. Your 

statement is essentially that helicopter pilots holding any FAA pilot certificate of PPL and above are 

safer than any pilot holding an FAA sport pilot certificate, but a select group of the latter are exempt 

from the minimum altitude rules. Your statement also ignores the fact that an aircraft supported in 

flight by an autorotating rotor maintains full control at any airspeed and is at least as safe,if not safer, 

than a powered parachute or weight-shift control aircraft at any altitude. 

The additional training required of helicopter pilots over gyroplane pilots, to the extent it exists 

at all, reflects only mastery of those tasks required for private pilots of gyroplanes that are not 

required for sport pilots of gyroplanes. According to Part 61, that training consists of night 

flight and towered airport operations, neither of which have any bearing on minimum safe 

altitudes for operation. It is the stated position of the FAA that sport pilots are tested to a 

standard that ensures the safety of the public. If this is not the case, as suggested by your 

characterization of sport pilots as less skillful, then the issue is Imprudent rulemaking with 

respect to sport pilot standards and/or lack of oversight/enforcement of such testing standards 

by the FAA. It is incumbent upon the FAA to correct any such deficiencies at once, as a 

matter of safety for all. It does not provide a basis for denying the petition. 

Your statement that the safely of helicopter routes could be compromised if the FAA allowed allowed 

much less capable gyroplanes to fly on these routes is at best an unsupportable assertion. A helicopter 

route is essentially no different than a VFR flyway through Class B airspace. VFR flyways are not 

restricted to aircraft of minimum performance capabilities but are nevertheless safely used by hundreds 

of pilots flying dissimilar aircraft daily across the United States. A helicopter route is also not limited to 

helicopters of minimum performance capabilities yet are also safely used daily by hundreds of pilots 

flying dissimilar aircraft. 

Gyroplanes are not less capable than helicopters of flight along designated helicopter routes 

through major population centers. Such routes were not developed for the purpose of 

hovering, but to allow efficient transit through such areas. Cruise speeds of gyroplanes are 

comparable to, if not faster, than many helicopters. Under current rules, there is no regulatory 

basis for denying gyroplanes access to charted helicopter routes. Perhaps you should look 

into that before making blanket statements about use of those routes. 

Your statement that gthe FAA finds that the height-velocity (HA^) curve you referenced only applies to 

[heUcopter] takeoffs and level flight with power. It is not appropriate to consider the WW curve in an 

autorotative landing as a result of an engine failure which is the focus of FAR 91.119h discloses a 

fundamental lack of understanding of rotary-wing aircraft operations. I am sure that the FAA Aircraft 

Certification Service, Rotorcraft Directorate, would be most relieved to not have to consider height-
velocity limitations during autorotation testing of helicopters. Since a gyroplane always lands from an 

autorotative descent and the flight manuals of FAA-certificated gyroplanes always include heightvelocity/graphs — and a helicopter in autorotation is in essence an inefficient gyroplane — what is the 

physical basis for your statement? Note that the paragraph beginning "It should be noted that, once a 

steady state autorotation has been established..," on page 11 -4 of the Rotorcraft Flying Handbook is 

provably wrong. Please feel free to execute a landing in a helicopter from a stable autorotation inside 

the avoid region of its height-velocity graph. Just don't be anywhere near me when you do it. Your 

discussion of the use of collective pitch by a helicopter pilot to manage glide angle during an 

autorotative descent is primarily of academic interest since the objective of a pilot during such a 

procedure is to maintain the minimum rotor rpm necessary as indicated on the rotor tachometer to 

provide adequate rotor thrust and control. In any event, an autorotative descent to a landing in a 

helicopter is an emergency procedure; an autorotative descent to a landing in a gyroplane is a normal 

procedure. Due to the lower disk loading necessary to provide adequate performance in a gyroplane and 

the fact that its rotor is optimized for autorotation, a cyclic flare to landing in such aircraft invariably 

results in minimal, if any, ground roll after touchdown. When a ground roll does occur, this is again a 

normal procedure for which the gyroplane is designed. This is not the case in a helicopter which unless 

operated in an ideal manner by the pilot, under favourable gross weight and atmospheric conditions, 

will skid or roll along the ground after touchdown is and highly prone to roll over 

For helicopter operations, the FAA's Rotorcraft Flying Handbook teaches that collective pitch 

is used to control rotor rpm, not glide path as you stated, while glide performance is a matter 

of airspeed control. The same is true for glide management in a gyroplane, only there is no 

need for any rotor rpm control at all. As to the touchdown itself, that same Handbook advises 

that ground roll for a gyroplane is routinely under 50 feet and with less than 20 mph airspeed, 

and that is without consideration of wind. One must wonder what you mean by very little or 

no ground run if under 50 feet doesn't qualify. 

The overriding concem of FAR 91.119 is to maximize the probability that after an engine failure an 

aircraft can land as safely as possible while minimizing hazards to both its occupants and 

persons/structures on the ground. Gyroplanes were invented to meet this objective and have always 

outperformed helicopters in such situations. Your response to my petition is sloppy, unprofessional, and 

ultimately a waste of time. I will refile this petition in light of the changes to FAR 91.119 and include as 

supporting material my original petition, your denial letter and my response thereto. 

Please note that copies of my petition will be sent to the organizations listed below for advisory 

purposes. I do not represent any of these organizations in this matter. 

The overall theme of your response to the petition seems to be that there are very few 

standard airworthiness certified gyroplanes at this time, and that small numbers do not justify 

a rule change. One must then wonder why the FAA has a recently-established powered-lift 

category in the regulations, given that there are exactly zero such aircraft that have received 

standard airworthiness certification worldwide. Is it the FAA's view that regulations to 

encourage development of some forms of not-yet-developed rotor-driven craft should be 

established, while regulations that inhibit practical and safe use of other already existing forms 
are to be left in place? How is such a preference determined and justified by the FAA? It 

would appear that you have made an official governmental determination that there is no 

future for certified gyroplanes to be developed, but that there is such a future for tilt-rotors, 

without any Congressional authorization to make that determination, or any market data in 

support. The courts refer to such actions as arbitrary and capricious. 

The conclusion I draw from your letter is that you hold experimental gyroplanes and their 

pilots in very low regard. 1 share that sentiment, but it does not justify denying relief to those 

of us who hold the highest pilot credentials authorized by the FAA and fly fully certified 

aircraft. 

Sincerely, 

an-Prerre Harrison 

cc: 

Airplane Owners and Pilots Association 

American Helicopter Society International 

Carter Aviation Technologies 

FAA Aircraft Certification Service, Rotorcraft Directorate 

Groen Brothers Aviation, Inc. 

Helicopter Association International