Development of EPA aircraft piston engine emission standards

Document

1. DEVELOPMENT OF EPA AIRCRAFT PISTON ENGINE EMISSION STANDARDS W i l l i a m Houtman O f f i c e of Mobile Source A i r P o l l u t i o n Control U.S. Environmental P r o t e c t i o n Agency INTRODUCTION On J u l y 17, 1973, a f t e r over 3 years of development e f f o r t , t h e Environmental P r o t e c t i o n Agency promulgated emission regulations f o r a i r c r a f t p i s t o n engines. The r e g u l a t i o n s f o r a i r c r a f t p i s t o n engines are t o become e f f e c t i v e f o r engines manufactured a f t e r December 31, 1979. The standards s p e c i f i e d i n t h e regulations are based on modest emission c o n t r o l technology which i s considered t o be f e a s i b l e t o i m - plement w i t h i n t h e s t a t e d t i m e .

AIRCRAFT EMISSIONS Before discussing c h a r a c t e r i s t i c p i s t o n engine emission levels and EPA Standards it i s necessary t o d e f i n e s p e c i f i c a l l y what is being measured. A t p r e s e n t , t h e EPA i s primarily concerned with emissions i n t h e v i c i n i t y of t h e a i r p o r t , and t h e emission t e s t cycle r e f l e c t s t h i s philosophy. Carbon monoxide, hydrocarbon,and oxides of nitrogen e m i s - s i o n rates are measured w i t h t h e engine operating at idle-taxi, t a k e o f f , climbout, and approach power modes with no consideration t o c r u i s e e m i s - sions. These engine loading conditions are obtained with t h e engine operating on an engine dynamometer o r test s t a n d . The emission rates a t each power s e t t i n g are multiplied by a s p e c i f i e d r e p r e s e n t a t i v e t i m e f o r t h e mode, giving t h e mass emissions f o r t h e mode. The emissions f o r t h e modes are summed t o give t h e mass emissions f o r t h e LTO cycle. To t a k e engine s i z e i n t o consideration i n e s t a b l i s h i n g standards, it w a s assumed t h a t t h e u s e f u l work performed by t h e a i r c r a f t is generally proportional

t o t h e engine power and one standard w a s - not set f o r a l l s i z e s of en-

gines as with passenger cars. Rather, t h e a i r c r a f t standards are based on t o t a l mass emissions p e r LTO cycle per r a t e d horsepower f o r t h e en- gine. The cycle can be i l l u s t r a t e d i n f i g u r e 1-1. Here w e have t h e power s e t t i n g and t i m e i n mode f o r each operating condition of t h e t e s t cycle. The EPA allows t h e manufacturer t o s p e c i f y t h e power s e t t i n g s f o r t h e t a x i - i d l e and climbout modes w i t h t h e provision t h a t climbout i s a t least 75 percent power.

A s p a r t of t h e development of a i r c r a f t emission r e g u l a t i o n s , measurements w e r e made on a t o t a l of 70 engines, representing approxi- mately nine d i f f e r e n t b a s i c models. The measurements were made by Teledyne Continental ( r e f . 1 ) and S c o t t Research Laboratories ( r e f . 2 ) .

S t a t i s t i c a l processing of t h e d a t a w a s performed by Cornel1 Aeronautical Laboratories ( r e f . 3). The majority of t h e d a t a presented i n t h i s dis- cussion w a s taken from t h i s e a r l y work.

Figure 1-2 is a t a b u l a t i o n of some of t h e r e s u l t s of t h e t e s t i n g .

The EPA standards are a l s o shown f o r reference. The boxed numbers indi- cate emission levels f a l l i n g w i t h i n t h e EPA standards. A comparison of t h e EPA standards and t h e b a s e l i n e test r e s u l t s reveals t h a t t h e a i r c r a f t p i s t o n engine standards are primarily a CO c o n t r o l with some reductions f o r HC and a s u b s t a n t i a l margin f o r increases i n NO . In a d d i t i o n , by comparing t h e standards of t h e i n d i v i d u a l pollutant$, i t can b e seen t h a t t h e CO levels are g r o s s l y higher than t h e HC o r NOx levels.

Figure 1-3 f u r t h e r i l l u s t r a t e s t h e emission c h a r a c t e r i s t i c s of p i s - ton engine a i r c r a f t . Here w e have p l o t t e d t h e f u e l s p e c i f i c emission rate as a function of engine a i r - f u e l mixture r a t i o . The d i f f e r e n t scales f o r CO t o t h e l e f t and HC and NOx t o t h e r i g h t should be noted.

The b a s e l i n e d a t a used indicated t h a t engines t y p i c a l l y operated w e l l on t h e f u e l r i c h s i d e of t h e stoichiometric mixture r a t i o . The d a t a a c t u a l l y revealed engines operating r i c h e r than shown here. To put air- can be made from c r a f t emissions i n perspective, a s i g n i f i c a n t point t h i s CO curve. An engine operating a t an a i r - f u e l r a t i o of 1 O : l is producing approximately 1300 pounds of CO p o l l u t a n t f o r every 1000 pounds of f u e l consumed. Leaning t h a t engine t o 1 3 : l (approximate b e s t power mixture r a t i o ) would reduce CO emissions by b e t t e r than 50 per- c e n t .

INFLUENCE O F PISTON AIRCRAFT EMISSIONS ON A I R QUALITY I n t h e s t u d i e s supporting t h e promulgation of t h e a i r c r a f t regula- t i o n s ( r e f s . 4 and 5) two a i r p o r t s w e r e examined, Van Nuys and T a m i a m i .

Based on t h e s e s t u d i e s , i t w a s determined t h a t t h e CO emissions from p i s t o n engine a i r c r a f t has a s i g n i f i c a n t influence on t h e carbon monoxide a i r i n and around t h e a i r p o r t property t o which l e v e l s i n t h e ambient workers and travelers i n t h e a i r p o r t v i c i n i t y would be exposed. I n pre- paring t h i s p r e s e n t a t i o n it w a s decided t o review t h e s e p a s t s t u d i e s and expand t h e a n a l y s i s t o i n v e s t i g a t e o t h e r a i r p o r t s as w e l l . The expanded study included t h r e e a d d i t i o n a l a i r p o r t s t o t h e Van Nuys and T a m i a m i a i r p o r t s . The s e l e c t i o n w a s somewhat a r b i t r a r y , b u t i t w a s , i n general, intended t o sample a i r p o r t s having s i g n i f i c a n t general a v i a t i o n p i s t o n engine t r a f f i c as compared t o l a r g e r a i r p o r t s dominated by commercial t r a f f i c . Figure 1-4 presents t h e r e s u l t s of t h e latest a n a l y s i s f o r t h e f i v e a i r p o r t s considered. A s can be expected, from t h e previous discus- t h e carbon monoxide emissions are s u b s t a n t i a l compared t o t h e hy- s i o n , drocarbon and oxides of nitrogen emissions.

Comparing t h e s e emissions w i t h t h e t o t a l r e g i o n a l CO emissions w i l l reveal t h a t t h e a i r c r a f t a i r p o r t c o n t r i b u t i o n is of t h e order of 1 per- c e n t , Unfortunately, u n l i k e t h e HC and NOx oxidant problem where disper- s i o n is involved, CO emissions are critical a t p o i n t s of heavy concentra- t i o n , and t h i s 1 percent concentrated i n one l o c a t i o n , such as an air- p o r t , is of concern. For example, i n t h e v i c i n i t y of t h e Van Nuys air- p o r t , which is a known CO "hot s p o t Y t 1 t h e p i s t o n a i r c r a f t c o n t r i b u t i o n is approximately 1 0 percent of t h e t o t a l CO emission, a f f e c t i n g a population of 67 000 people. A s you draw your r e f e r e n c e area c l o s e r and c l o s e r t o t h e a i r p o r t t h e c o n t r i b u t i o n of a i r c r a f t emissions of course increases.

Another example i s t h e Fairbanks Airport which is a l s o located i n a CO troublespot. I n a l l of North Alaska t h e estimated CO emissions, excluding a i r c r a f t , are 6000 tons per year f o r 1985 and t h e CO concen- t r a t i o n s are s t i l l expected t o be w e l l above a i r q u a l i t y l i m i t s . It is estimated t h a t p i s t o n engine aircraft w i l l c o n t r i b u t e 1400 t o n s p e r year a t t h e Fairbanks a i r p o r t , o r one-third of t h e t o t a l allowable CO f o r North Alaska. Granted, I may b e accused of s e l e c t i n g only s p e c i a l cases t o make a general argument, b u t , considering t h e modest level of c o n t r o l required, t h e f u e l b e n e f i t s a s s o c i a t e d w i t h t h e c o n t r o l s and t h e disadvantages of o t h e r a l t e r n a t i v e s t o reducing emissions, t h e standards w e r e and s t i l l are considered warranted. The EPA had assumed t h a t modest standards would be less detrimental t o t h e industry than l i m i t a t i o n on operation a t a l l c r i t i c a l a i r p o r t s . I f t h e Fairbanks problem were t y p i c a l of a g r e a t e r number of regions, t h e n a t i o n a l regu- l a t i o n would, of course, b e much more s t r i n g e n t . To conclude t h i s a i r t h e f i n a l q u a l i t y discussion I would l i k e t o quote from t h e preamble of a i r c r a f t r u l e making published on J u l y 1 7 , 1973. "In t h e development of t h e r e g u l a t i o n s it w a s concluded t h a t emissions from a i r c r a f t and air- c r a f t engines should be reduced t o t h e extent p r a c t i c a b l e w i t h present and developing technology." I n t h e Proposed Rule Making of Dec. 12, 1972, it w a s stated t h a t t h e p i s t o n engine standards are considered by EPA t o be a t t a i n a b l e w i t h e x i s t i n g technology w i t h some improvement i n engine cooling concepts and improved f u e l management. How t h e standards w e r e a c t u a l l y e s t a b l i s h e d , assuming t h i s emission c o n t r o l concept, i s described i n the" following s e c t i o n .

SELECTION OF EMISSION STANDARDS A s already s t a t e d , t h e set of p i s t o n engine standards s e l e c t e d were based on a technologically f e a s i b l e and economically reasonable c o n t r o l of carbon monoxide. The approach t o s e l e c t i n g t h e standard can be i l l u s - t r a t e d by returning t o f i g u r e 1-3. The b a s e l i n e s t u d i e s revealed t h a t p i s t o n a i r c r a f t o p e r a t e over a wide range of f u e l - a i r r a t i o s . The base- l i n e t e s t i n g found engines were operating i n t h e range of f u e l - a i r r a t i o s A f t e r reviewing a v a r i e t y of of 0.08 t o 0.14 during ground operations.

p o t e n t i a l c o n t r o l systems it w a s concluded s u b s t a n t i a l CO reductions could be realkzed i f t h i s range of t y p i c a l f u e l a i r r a t i o s could be nar- rowed. Thus,improvements i n f u e l management w e r e determined as reason- a b l e c o n t r o l s t o impose on a source which has minimal impact on n a t i o n a l a i r q u a l i t y but c l e a r l y s i g n i f i c a n t impacts on c e r t a i n c r i t i c a l locations.

The s e l e c t i o n of t h e a c t u a l levels of t h e standards w e r e based on f i g - ure 1-3. The f u e l - a i r r a t i o of 0.077 t o 0.083 w a s chosen as a reasonable mixture r a t i o f o r engine operation e s p e c i a l l y s i n c e some engines a l r e a d y performed i n t h i s range. Thus, using t h e s e values and o t h e r b a s e l i n e en- gine c h a r a c t e r i s t i c s , t h e EPA standards f o r C O Y HC, and NOx w e r e calcu- l a t e d . Figure 1-5 i l l u s t r a t e s t h e standard s e l e c t i o n more d i r e c t l y than t h e previous f i g u r e . Here w e have c h a r a c t e r i s t i c p i s t o n engine emissions i n terms of t h e r e g u l a t o r y parameter and f u e l - a i r r a t i o . A s shown,the average mixture r a t i o t o achieve t h e CO standard is about 0.082. This value i s r i c h e r than both b e s t power and b e s t economy.

The mixture r a t i o t o achieve t h e HC standard i s even r i c h e r , t h u s f u e l management c o n t r o l t o achieve t h e CO levels should e a s i l y c o n t r o l t h e HC emissions. Fig- ure 1-6 f u r t h e r i l l u s t r a t e s how t h e s e c o n t r o l s w i l l i n f l u e n c e engine per- formance. A s shown,current engines o p e r a t e over a wide range of f u e l - a i r r a t i o s i n t h e LTO c y c l e . The emission standards narrow t h i s range forcing more of t h e engines toward t h e b e s t economy and b e s t power operating p o i n t s .

Recognizing t h a t t h e a i r c r a f t p i s t o n engine has varying o p e r a t i o n a l requirements, it i s not reasonable t o suggest t h a t an engine should a t t h e s a m e f u e l - a i r r a t i o over a l l operating conditions.

operate To i d e n t i f y t h e modes which are c r i t i c a l from t h e standpoint of achieving t h e EPA standards, f i g u r e 1-7 w a s prepared. Again, t h i s manipulation of d a t a w a s based on t h e measurements of in-use engines. The major p o i n t t o b e made, is t h a t t h e climbout, taxi-idle, and approach modes are t h e s i g n i f i c a n t operating conditions, with r e s p e c t t o emissions. Thus, rea- sonable f u e l cooling t o suppress detonation can still be u t i l i z e d f o r t h e f u l l power takeoff mode as long as leaning i s achieved i n t h e o t h e r modes. Figure 1-8 is an o u t l i n e of a sample c a l c u l a t i o n of CO emissions r e s u l t i n g from modal f u e l management.

What i s being suggested i s a s p e c i f i c f u e l - a i r mixture f o r each Based on f i g u r e 1-9 taken from an a i r c r a f t engine maintenance mode.

manual, t h i s i s apparently not a new concept. It i s presently u t i l i z e d t o achieve design goals o t h e r than emissions. A t low power s e t t i n g s o r mixtures are maintained r i c h t o produce smooth engine ac- low a i r flow, c e l e r a t i o n and possibly cooling. A t midrange o r c r u i s e , mixtures are leaned f o r economy; and a t high power modes, mixtures are enrichened again f o r detonation suppression.

The following series of f i g u r e s 1-10 t o 1-12 i l l u s t r a t e f u e l flow schedules t y p i c a l of in-use a i r c r a f t . Again, w e are dealing with test r e s u l t s from t h e b a s e l i n e measurements. The 0-200 engine d a t a on f i g u r e 1-10 supports t h e f u e l flow schedule j u s t described (i.e., r i c h i d l e , l e a n mid-range, and r i c h f u l l power). I n reviewing t h i s summary of in- it should be r e c a l l e d t h a t t h e f u e l - a i r r a t i o f o r b e s t use engines, power i s 0.076 f u e l - a i r and b e s t economy is 0.064.

It may be p o s s i b l e t o u t i l i z e these same programming mechanisms f o r emission c o n t r o l s by improved c a l i b r a t i o n o r modified scheduling.

For 'instance, a t t h e t a x i - i d l e conditions where r i c h mixtures have been used t o supplement cooling air and provide smooth low power oper- a t i o n , emissions should a l s o be considered i n t h e f u e l management sys- t e m design. Under approach conditions, mixtures are generally enriched t o provide smooth engine operation which w i l l a s s u r e response t o sudden full-power needs. Methods o t h e r than r i c h mixtures such as accelera- t i o n pumps should be sought t o s a t i s f y t h e s e design requirements.

THE FUTURE O F THE STANDARDS The s t a n d a r d s . i n e f f e c t f o r engines produced after December 31, 1979, are based on technology which i s considered f e a s i b l e f o r t h e pis- ton engine powered aircraft; namely, f u e l management. The EPA w i l l con- t i n u e t o monitor progress of t h e industry and supporting government agencies i n t h e i r attempt t o develop engines capable of complying t o t h e A s s t a t e d i n t h e preamble of t h e f i n a l r u l e making, "If EPA standards.

i t should become evident t h a t t h e standards as promulgated cannot be achieved a t t h a t t i m e which are s a f e and i n o t h e r resFects air-worthy, a d d i t i o n a l r u l e making a c t i o n w i l l be considered t o ensure t h a t t h e b e s t technology i s r e f l e c t e d i n t h e standards." This p o s i t i o n on t h e p a r t of t h e EPA should n o t be mistaken. W e continue t o f e e l t h e stand- a r d s are achievable with reasonable c o n t r o l methods. It w i l l take sound technical arguments with supporting d a t a t o modify t h i s p o s i t i o n . The f a c t t h a t e x i s t i n g engines cannot be tuned t o achieve these standards i s not s u f f i c i e n t reason t o consider new r u l e making. It is expected, a t least i n some engine models, t h a t hardware changes w i l l be required t o achieve t h e standards.

I f t h e EPA determined t h a t a change may be j u s t i f i e d , possibly stimulated by an industry p e t i t i o n , t h e r u l e making process would be i n i t i a t e d with a Notice of Proposed Rule Making (NPRM). A t t h a t t i m e information would be s o l i c i t e d from i n t e r e s t e d p a r t i e s which normally includes t h e a f f e c t e d manufacturers, t h e i r t r a d e organizations, environ- mental groups and p r i v a t e c i t i z e n s . After evaluating t h e pro and con arguments presented i n response t o t h e proposed a c t i o n and performing in- depent t e c h n i c a l a n a l y s i s a revised r u l e making package would be prepared.

Forums such as w e are engaged i n here are not p a r t of t h e r u l e making process b u t do perform a u s e f u l means f o r exchange of t e c h n i c a l informa- t ion.

A s some of you may be aware, t h e EPA r e c e n t l y held public hearings concerning t h e a i r c r a f t t u r b i n e engine standards. A s a r e s u l t of t h a t hearing, t h e r e is i n process a thorough assessment of t h e n e e d / j u s t i f i c a - t i o n f o r a N P R M f o r modifications of t h e a i r c r a f t t u r b i n e engine regula- t i o n s . The changes presently under consideration relate t o t h e t u r b i n e i s one a s p e c t of t h e p i s t o n standards which may engines; however, t h e r e be addressed i n t h i s NPRM. A s is hopefully apparent, a f t e r hearing my earlier comments, t h e p i s t o n engine r e g u l a t i o n s are primarily d i r e c t e d t o CO c o n t r o l . The HC and NO, standards were set a t l e v e l s a n t i c i p a t e d as a r e s u l t of t h e CO c o n t r o l s . A t t h e t i m e t h e standards were estab- l i s h e d , t h e general approach w a s t o set c o n t r o l s f o r each of t h e regu- l a t e d p o l l u t a n t s , p r i m a r i l y t o prevent trade-offs t h a t might unnecessarily i n c r e a s e one p o l l u t a n t while reducing another. However, r e c e n t l y , when emission standards w e r e developed f o r motorcycles,it w a s decided not t o set a NOx standard because t h e e f f o r t t o c o n t r o l t h a t p o l l u t a n t from motorcycles could n o t be j u s t i f i e d by t h e a i r q u a l i t y impact a n a l y s i s which had been made. This same argument can be considered r e l a t i v e t o CO is t h e p o l l u t a n t of concern.

t h e p i s t o n a i r c r a f t r e g u l a t i o n s .

Standards f o r HC and NOx w e r e set t o e s t a b l i s h "trade-off boundaries."

Removing t h e s e standards a l t o g e t h e r would allow g r e a t e r f l e x i l i b i t y f o r t h e s e l e c t i o n of emission c o n t r o l systems.

I f t h i s a c t i o n w e r e taken, i t would avoid t h e discarding by de- s i g n e r s , of good CO c o n t r o l systems, which may be marginal i n compliance with t h e HC and NO, standards. Also, during f u t u r e compliance t e s t i n g , HC o r t h e c o s t s a s s o c i a t e d with t h e r e j e c t i o n of an engine f a i l i n g t h e NO, l i m i t s would be d i f f i c u l t t o j u s t i f y when considering t h e b e n e f i t s received from s l i g h t reduction i n HC o r NO, emissions which may be r e a l i z e d .

Whether o r not EPA as a n organization w i l l consider removing t h e e x i s t i n g l i m i t a t i o n s on HC and NO, emissions from p i s t o n a i r c r a f t en- gines is something t h a t I a m n o t i n a p o s i t i o n t o say. Rather, I a m sharing with you candidly t h e considerations t h a t I and m y colleagues W e are w r e s t l i n g with a t t h e t e c h n i c a l s t a f f level a t which w e work.

w i l l d i g deeply i n t o t h e p o t e n t i a l a i r q u a l i t y impact of any such change before even proposing it t o t h e executive levels of t h e EPA, f o r w e know as w e l l as you t h a t t h e removal of t h e HC and NO, standards would be a complicated process involving i n p u t s from marry l e v e l s and organiza- t i o n s of t h e government.

CONCLUSIONS P i s t o n engine l i g h t a i r c r a f t axe s i g n i f i c a n t sources of carbon monoxide i n t h e v i c i n i t y of high a c t i v i t y general a v i a t i o n a i r p o r t s .

S u b s t a n t i a l reductions i n carbon monoxide can be achieved by f u e l mixture leaning using improved f u e l management systems.

The air q u a l i t y impact of t h e hydrocarbon and oxides of n i t r o g e n emissions from p i s t o n engine l i g h t a i r c r a f t appear t o be i n s u f f i c i e n t t o j u s t i f y t h e design c o n s t r a i n t s being confronted i n present c o n t r o l system developments.

REFERENCES 1. "Collection and Assessment of Aircraft Emissions." Prepared for the Environmental Protection Agency by Teledyne Continental Motors, October 1971, Contract 68-04-0035.

2 . "A Study of Aircraft Powerplant Emissions."

Prepared for the Environ- mental Protection Agency by Scott Research Laboratories Inc., January 1971, Contract No. 68-04-0037.

3. "Analysis of Aircraft Exhaust Emission Measurements." Prepared for the Environmental Protection Agency by Cornel1 Aeronautical Labora- tory, Inc., November 1971, Contract No. 68-04-0040.

4 . "The Potential Impact of Aircraft Emissions Upon Air Quality." Pre- pared for the Environmental Protection Agency by Northern Research and Engineering Corporation, December 1971, Contract No. 68-02- 0085.

5. "Aircraft Emissions: Impact on Air Quality and Feasibility of Con- trol." United States Environmental Protection Agency.

DISCUSSION

Q - B. Rezy: When you mentioned an average f u e l - a i r r a t i o of 0.077 t o

0.083, how w a s t h a t average defined?

A - W. Houtman: It w a s not weighted as i n t h e way TCM does t h e i r work.

The d a t a were p l o t t e d a t a given power s e t t i n g and f u e l - a i r r a t i o on a modal basis.

but n o t

Q - B. Rezy: You are assuming a constant f u e l - a i r r a t i o f o r a l l modes?

A - W. Houtman: That would be an e f f e c t i v e average, yes.

COMMENT - B. Rezy: The f u e l - a i r r a t i o you've mentioned corresponds t o

an equivalence r a t i o of 1.23, and we w i l l show later that none of t h e emissions were m e t a t t h a t equivalence r a t i o .

Q - K.. Stuckas. You r e f e r r e d t o carbon monoxide concentrations a t t h e

f i v e a i r p o r t sites. Were CO emissions a c t u a l l y measured a t t h e s e sites? If s o , how were you a b l e t o determine what proportions of t h e CO levels were due t o p i s t o n engine a i r c r a f t ?

A - W. Houtman: No, t h e CO levels were not measured f o r t h i s study o r

a n a l y s i s ; they were based on FAA s t a t i s t i c s f o r t h e t r a f f i c a t t h e f i v e a i r p o r t s . W e looked a t t h e types of a i r c r a f t f l y i n g , t h e d i s - t r i b u t i o n of a i r t r a f f i c , and t h e number of engines on e a c h - a i r - c r a f t ; w e then broke t h e s e down by engine type, c a l c u l a t e d t h e t o t a l s , and compared them t o t o t a l r e g i o n a l CO emissionsi There are some CO measuring sites near t h e Van Nuys A i r p o r t , which is one of t h e problem areas.

Q - K. Stuckas: Were you a b l e t o determine what p o r t i o n of t h e CO

levels w a s due t o p i s t o n engine a i r c r a f t as opposed t o passing t r a f f i c ?

A - W. Houtman: W e d i d make a n a n a l y s i s , but it w a s not based on mea-

W e could c a l c u l a t e t h e CO, but again a l o t of surments of 'CO.

assumptions would be involved. W e can break it up t o some e x t e n t , and t h a t ' s what t h e 1 0 percent p i s t o n engine c o n t r i b u t i o n r e f e r s to.

COMMENT - M. Steele: The GAMA environmental subcommittee has reviewed

t h e a v a i l a b l e d a t a f o r t h e pre-1973 time frame on which i t is believed t h e standards f o r a i r c r a f t p i s t o n engines w e r e made i n 1973. The re- viewer revealed t o us t h a t t h e d e c i s i o n s were made on very incomplete d a t a and a t a t i m e when instrumentation and measurement' techniques were Today t h e r e is a g r e a t l y expanded knowledge f a r from f u l l y e s t a b l i s h e d .

in t h e subject. It is hoped t h a t t h e t h r e e agencies w i l l g i v e c a r e f u l t o consideration n o t only t o t h i s expanded t e c h n i c a l d a t a base but a l s o t h e broader aspects of s a f e t y , schedules, c o s t s , and f a c i l i t y and man- power l i m i t a t i o n s . The member companies of GAMA welcome t h e opportunity afforded a t t h i s meeting and hope t h a t t h e information provided w i l l assist i n realistic d e c i s i o n s on t h e s u b j e c t of such n a t i o n a l concern.

It is hoped t h a t t h e proceedings w i l l recognize t h e f a c t t h a t general a v i a t i o n is only a s m a l l p a r t of t h e n a t i o n a l t r a n s p o r t a t i o n system amd t h a t a i r c r a f t p i s t o n engine p o l l u t i o n l e v e l s should be placed i n t r u e perspective with r e s p e c t t o t h e rest of t h e t r a n s p o r t a t i o n system and t h e respected emission improvements be derived therefrom.

Q - D. Powell: W a s t h e 1 percent CO i n t h e v i c i n i t y of the a i r p o r t s

based o n " t h e c a l c u l a t e d emissions from t h e a i r c r a f t and then divided by some area, and what w a s t h e area of t h e a i r p o r t i n square miles?

The 1 percent value is based on t h e a i r q u a l i t y region A - W. Houtman: where t h e a i r p o r t is located. For i n s t a n c e , t h e Van Nuys Airport is located i n t h e Los Angeles a i r q u a l i t y region and t h e CO emissions are of that order. These are estimated projected emissions f o r estimate of 1985. One EPA t h e CO emissions i n 1985 f o r a given model is about 1 000 000 tons a year compared t o less than 10 000 tons f o r Van Nuys alone. The concentration of CO is a l o c a l problem and not a r e g i o n a l problem.

This is why t h e HC and NOx are not con- sidered t o be critical.

Q - D. Powell: T w a s t r y i n g t o g e t some i d e a of how l a r g e an area t h e

CO w a s spread over.

A - W. Houtman. Possibly 100 square m i l e s , I ' m not s u r e what t h e Los

Angeles region is. W e d i d n ' t take a l l t h e general a v i a t i o n t r a f f i c i n t h e Los Angeles a i r q u a l i t y c o n t r o l region, but j u s t a t one of t h e a i r p o r t s . There are o t h e r general a v i a t i o n a i r p o r t s i n t h a t a i r q u a l i t y region and i f w e summed these i t would still be of t h e o r d e r of 1 t o 3 percent.

Q - L. Duke: Were t h e s e p r o j e c t i o n s f o r 1985 based on having a i r c r a f t c o n t r o l s o r standard a i r c r a f t compared a g a i n s t automotive controls?

A - W. Houtman: Even by 1985 t h e r e w f l l be very l i t t l e impact of t h e

a i r c r a f t standards because f i r s t they don't become e f f e c t i v e u n t i l e s s e n t i a l l y 1980 and then 5 years of production compared t o t h e t o t a l a i r c r a f t population would not be very much.

Q - R. Tucker: I ' d l i k e t o make A general comment concerning t h e i n f o r -

mation you have on f i g u r e 2 on t h e CO level f o r t h e 10-520. You state t h a t it i s a l e a n climb and I assume t h a t i t i s b a s i c a l l y a b a s e l i n e mode c y c l e with t h e climb mode leaned o u t .

A - W. Houtman: I don't recall a c t u a l l y but I suspect t h a t ' s it. It's

c e r t a i n l y a b a s e l i n e engine.

Q - R. Tucker: Comparing t h e s e d a t a t o our 10-520 d a t a , w e have a value

i n t h e same u n i t s of 0.079 € o r baseline. I f a l l t h e modes w e r e leaned out t o t h e point of Imposing a s a f e t y problem t h e CO v a l u e would be 0.035 and t h e l e a n l i m i t o f . o u r model spec gave u s a 60 level of 0.053. All t h r w n f those are considerably larger than t h e 0.028 t h a t you quoted t h e r e .

A - W. Houtman: It's $from t h e d a t a taken a t t h e t i m e . It's e i t h e r from

data.

t h e Cornel1 r e p o r t o r possibly from t h e Continental

Q - R. Tucker: I would l i k e t o know what t h e information i n f i g u r e 3 is

based on.

A - W. Houtman: This w a s taken from t h e S c o t t r e p o r t i n which a l l t h e

d a t a w e r e p l o t t e d . You can see t h e CO d a t a up i n t h e upper l e f t corner p l o t s q u i t e w e l l . You might g i v e some argument on the HC and NOx, but t h e r e is another curve f o r carbureted engines and in- j e c t e d engines. If you overlay t h e i n j e c t e d on t h e carbureted engine curve y o u ' l l see t h a t they a l l f a l l on each other. So t h e CO curve is p r e t t y good. The d a t a f o r t h e i n j e c t e d and carbureted engines p l o t q u i t e w e l l as a s t r a i g h t l i n e .

TEST CYCLE POWER AND TIME IN MODE I

I

CLIMDOUT TAXI/ID LE(0 UT) ( 12.0 Oe3 5.0 6.0 4.0 TIME IN MODE ( M I N I Figure 1-1 TYPICAL AIRCRAFT PISTON ENGINE EMISSIONS CQ HC .0019 EPA STANDARD ,042

0-200 .OB 1 1 . 0 0 1 5 1

I.,,,,]

0-320 ,074 .0042 10-360 .065

0-470 .054 [XI

10.540 .002 .0035 .0026 0-540 .07 1 ,0029

10-620 (LEAN CLIMB 1 1 x 1

Figure 1-2 PISTON ENGINE EMISSION CHARACTERISTICS 1400 140 1200 120 1008 100 800 A0 GOO fa Y L 400 40 L a I 200 20 I- 8 1 $ 1 101 ll:1 121 131 14:l lkl nin FUEL nnitn Figure 1-3 A i r P o l l u t i o n Contribution of P i s t o n Engine A i r c r a f t a t Five Selected A i r p o r t s Tons /Year

HC Year Rank co NOx

- - - - _I

Van Nuys 3 1974 56 2500 10 3300 13 1980 74 1985 83 3700 15 T a m i a m i 31 1974 35 1600 6 1980 55 2400 9 1985 78 3500 13 San J o s e 10,28 1974 64 2800 12 3800 15 (2 a i r p o r t s ) 1980 84 1985 94 4200 17 Phoenix 1400 5 9 1974 31 1900 8 1980 44 1985 50 2200 9 Fairbanks 133 1974 14 600 3 1980 25 1100 4 1985 31 1400 5 *Projections based on FAA t e r m i n a l area f o r e c a s t f o r 1976 through 1986 Figure 1-4 AIRCRAFT PISTON ENGINE CYCLE EMISSIONS .0042

I

w . O O N -1 >.

W 0 P .0010 .0002 .OG .07 .OO .09 .10 -11

FUEL - AIR RATIO

I I I 14 12 10 AIR-FUEL RATIO Figure 1-5 AIRCRAFT PISTON ENGINE FUEL-AIR MIXTURES 180 BEST POWEn D .

I K ' z W a s: rn n .

l -

k

z W a m W . . I 80 100 a sp I-

e

I I 1 I I I I I .OS .06 .07 .08 .09 .10 .ll .12 .13 .14 FUEL-AIR RATIO IN-USE AIRCRAFT

-

LTO OPEflATlNC RANGE Figure 1-6 % GO EMISSIONS BY MODE TAXlllDLE (OUT4 IN)

I

3 3.S%

TAKE OFF

I

- 1 41.4%

CLIMB OUT

I I

APPROACH 28.6% 10 20 30 40 Figure 1-7 Sample C a l c u l a t i o n LTO Cycle Emissions

-

TIM h r A/F

I------

bf 'bhp h r

-

.45 .05 .27 .003 13:l .530 T a x i / i d l e

I

.005 .004 1O:l 1.300 .62 1.00 Takeoff ( d e t o n a t i o n s u p p r e s s i o n ) .083 .020 12.6:l .650 .46 .80 Climbout ( b e s t power) .45 .40 .10

.Approach 13:l I .530

- - %o x * f x bhp mode x hr = *CO/LTO

Mode bhp-hr bhp r a t e d mode r a t e d bhp fif fuel s p e c i f i c emissions from F i g u r e 3

- = >

- Mf = b r a k e s p e c i f i c f u e l consumption from F i g u r e 3

bhp-hr bhp mode = s p e c i f i e d mode power s e t t i n g bhp r a t e d TIM = s p e c i f i e d t i m e i n mode F i g u r e 1-8 LOW Air-flow, lb/hr High ~ y p i c a l fuellair mixture curve f o r injection-type carburetor.

Rich Rich Fuellair Fuellair Lean Lean Low Air-flow, lblhr High Low Air-flow, lb/hr iiigh Typical f u e l l a i r mixture curve I d l e mixture cwrve f o r float-type carburetor.

Figure 1-9 .

PRESENT PISTON ENGINE FUEL-AIR CALIBRATIONSI 0-200 .12 ' .* . .

. * 0 ..

....

I . .

0 .10 .

I - d . .

9 .

-l ' * .

Lu 0.

3 .08 . ..

L L ..

. .

* * ..

. * . .

* 0 .

0 . .

0 . t . * : a*** , '. .....

.-.

.06 ..

0 .

I I I I 1 f 2 4 6 AIR-FLOW (lb/hr x 100) .20 .18 10-360 .16 .14 .12 .10 .08

.06 I I I I I I I I I

0 2 4 6 8 10 12 14 16 AIR-FLOW (Ib/hr x 100) Figure 1-10 .20 PRESENT PISTON ENGINE FUEL-AIR CALIBRATIONS . I 8 . I 6 E !

. I 4 I-

s

ce . I 2

a A w .IO U e .

. 0 8 .06 AIR-FLOW (Ib/hr x 100) .2a . I 8 10470 . I 6 I-

2 . I 4

s

.I2 w L L . I 0 . 0 8 . 0 6 0 2 4 6 8 1 0 1 2 1 4 AIR-FLOW (Ib/hr x 100) Figure 1-11 PRESENT PISTON ENGINE FUEL-AIR CALIBRATIONS 0-540

0 . . * e *

0 2 4 6 8 10 12 14 16 AIR-FLOW (Ib/hr x 100) I 0-540 0 ..

cr

a .I2 ..

* .

.. .

.. . e .