While having dinner in Apartment 4A, Bernadette tucks Raj’s label into the back of his shirt. This action is the closest that Raj has had to sex in two years. Raj's comment makes Howard very uncomfortable. Raj wants to talk about something other than his depressing love life, so Sheldon brings up the topic of Penny's depressing acting career. Penny did turn down a part in the sequel to Serial Apeist (Serial Ape-ist 2: Monkey See, Monkey Kill), her earlier movie where she appeared topless. She would have been the cross clone of her previous character and the gorilla, running around the film with huge gorilla hands and feet. Per Penny, "total crap". Leonard wants to know why she won't take this part since a lot of successful actors start out in bad movies. Also Penny must know what she is doing turning down paid work and burning through her savings. The gang looks up expecting a fight. Discussing failed careers, Sheldon brings up Howard's work as just an engineer. Bernie then wants to know why Sheldon is also so mean to her husband. Leonard then adds that he is excited that Penny got offered a part and only surprised that she would rather stay home and do nothing. Penny now leaves. Sheldon then gives Bernadette details of ten years of his torture by Howard. When they first met, he said that Sheldon looked like a cross between C3P0 and Pee-Wee Herman, See Three Pee Wee Herman. Since then he has messed up his lecture slide presentations and subscribed Sheldon to inappropriate magazines.
Amy has Raj walk her to her car. Amy wonders about his on-line dating site which Raj has given up checking. Amy had also lost heart over her web profile, but eventually she did find Sheldon even though they have only kissed once in three years as points out by Raj.
Howard visits Sheldon's office and wants them to be better friends. Sheldon thinks what they have now is too much. Howard really wants to move their friendship forward and first suggests that they stop insulting each other. Also, NASA is flying Howard down to Houston to give a talk and he has two plane tickets. Since Bernadette can't go, he is asking Sheldon and will give him a tour of NASA and take him to see his mother. Sheldon agrees to go as long as it's not a prank that might get him deported to South America.Raj visits Amy and shows him a girl's profile who had responded to Raj's dating site. Emily is both cute and smart and has no large Adam's apple according to Raj. Raj runs his fancy poetic response by Amy who thinks that he should just simply ask her out for coffee and not sound desperate and creepy. Raj then asks Amy to be his wingman and talk to her for him.
Penny returning with Sheldon from the pharmacy with some medicine for his trip. Penny's engine starts to make rattling noises and smoking. Sheldon reminds her of the check engine light again. He wonders if the problem is minor and then the car stops producing a lot of smoke. The check engine light finally goes off.
In the apartment the guys are playing a board game and Sheldon keeps referring to "his good friend Howard". Raj is jealous and tries to show everyone that they are such good friends that they finish each other's sentences. Raj wonders if he can go too. However it's a little late to get planes tickets.Penny reports that her car is not worth repairing. She tries to get the role in Serial Apeist 2, but it was given to someone else. Penny says that now someone is going to go on Letterman and tell how she got her break in a dumb gorilla movie because of an actress who thought it was beneath her. She has to get her old job back at The Cheesecake Factory though Leonard does offer to take her to auditions.
Amy responds to Emily who doesn't think she is right for Raj since he is too shy to talk to her directly. Amy is going to try and talk him up again when she meets her for coffee because she has a lot in common with Amy.Bernadette and Howard pick Sheldon up. He won't come down until Howard proves that Bernadette doesn't have an air fresher hanging from her rear view mirror. Sheldon shows up and is excited about the trip. Howard remarks that it isn't everyday he gets to tour NASA with a real astronaut. Sheldon wonders who that astronaut is forgetting that Howard went into outer space. On the plane Sheldon needs to visit the little physicists' room. Howard gets a bit irritated because despite his attempts to be a better friend, Sheldon still constantly says irritating things. Howard mentions that he is an astronaut, but Sheldon didn't acknowledge it. When Sheldon was a child astronauts were his heroes and Howard going into space was hard for him. Then he adds that it made him realize that they will send anyone up there which causes Howard not to let him out of his seat. They start to feel some turbulence which Sheldon first denies it bothers him. Howard experienced worse returning from space plummeting through the atmosphere. As the bumping gets worse, they both acknowledged their fears.
Leonard is picking up Penny so she can get her old job back. She is thrilled since she left telling the bitches goodbye and that she'll see them at the Oscars. Leonard tries to make Penny feel better by lightening the mood; however he is treading a thin line between her loving him because he's trying, and her hating him for making her feel worse. He opens the door of a strange car that Penny mentions is not his. He pulls out a key and tells her that he thought they would take her car. The car is nothing fancy, but she can use it to go to auditions and doesn't have to return to her old job. Penny is both shocked and touched; she hugs Leonard.Emily and Amy are having coffee and she still tries to match the two of them together. She calls Raj a sweet and regular guy who then shows up uninvited. Raj tells her that a passive guy would not barge in; however he still comes across creepy. She calls him a weird guy with no boundaries and leaves. She also ditches Amy for a something they were going to do. Raj ruined any chance for friendship for either of them.
On the airplane, the turbulence is very bad as both Howard and Sheldon apologize for everything they ever did to each other. Sheldon feels that if Howard wasn't in his life, he would have a big hole in it. Finally the plane flight settles down and they are still holding hands together. Sheldon doesn't want to let go, and neither does Howard.
- Guest starring:
- Teleplay: Jim Reynolds, Steve Holland & Maria Ferrari
- Story: Steven Molaro, Eric Kaplan & Tara Hernandez
- Jesse Schedeen of IGN:"...while "The Friendship Turbulence" did have one subplot focused on Leonard and Penny, it balanced that out with others that paired Sheldon with Wolowitz and Amy with Raj. The end result was a nice mix of the familiar and the new. Unfortunately, the decision to focus equal attention on all three plot lines ensured that none really received the attention it deserved...Sheldon and Wolowitz did their best to bury the hatchet this week and try and build a friendship around something more substantial than trading insults...And it was funny to learn that their decade-long feud started when Wolowitz called Sheldon "C-3Pee Wee Herman." Harsh, maybe, but pretty darned accurate...Finally, we got more of the always enjoyable Raj/Amy pairing. I like seeing these two bond over their mutual social awkwardness and loneliness...the decision to focus equally on all three subplots robbed the episode of a lot of its potential. The end result was still entertaining, just not the gem it could have been."
- Dhruv Rao of The DR Club criticized the use of drama, and gave the episode a C. 
- IMDb user reviews
- Title Reference: Howard and Sheldon deals with the friction in their friendship and they both experience some turbulence while flying on a plane to Houston, Texas.
- Taping date: February 19, 2014
- Chuck Lorre's vanity card.
- This episode was watched by 18.09 million people with a rating of 5.3 (adults 18-49).
- Total viewers including DVR users 23.78 million.
- The Big Bang Theory was ranked #1 for the week ending March 9, 2014.
- This episode aired in Canada on March 6, 2014 with 4.035 million viewers with a weekly ranking of #1.
- Episode transcript 
- Sheldon wears his yellow Sinostro t-shirt , a Green Lantern shirt featuring the logo with the Green Lantern oath, his Atmospheric CO2 shirt from Thinker Collection , and his Astro Smash t-shirt (on the plane).
- First appearance of Emily Sweeney.
- First time Sheldon has knocked (or in this case tapped) 3 times and said Howard's name.
- Penny's car finally breaks down due to her "check engine" light which Sheldon, Amy and Beverly Hofstadter all have been mentioning to her for years.
- Howard tells Sheldon he could visit his mom when they are in Houston, which he does in the next episode (S7E18).
- Third time Sheldon has peed his pants; the first time was in "The Bozeman Reaction" (S3E13) and the second was in "The Good Guy Fluctuation" (S5E7).
- Penny is offered a part in the sequel to her first movie "Serial Ape-ist" previously mentioned in the "The Hofstadter Insufficiency" (S7E1).
- Raj previously dated a girl called Emily in "The Wiggly Finger Catalyst" (S5E4).
- First time that Bernadette has worn her hair in a ponytail.
- The dining table Leonard bought in the previous episode is now gone, after Sheldon got his way, as usual.
- First episode where characters are on an airplane.
- Laura Spencer is the third actress to play a character interested in Raj that has appeared on the TV series "Switched at Birth". Also Tania Raymonde as Yvette in "The Locomotive Manipulation" (S7E15) and Katie Leclerc as Emily in "The Wiggly Finger Catalyst" (S5E4).
- Sheldon feels that the character Penny would have played in the film (a half gorilla with larger hands and feet) was perfect for her; Penny's large farm hands and her father's large feet have been previously referred to by him.
- First episode where Sheldon and Howard appear to be friends.
- Amy states that she had almost given up on online dating before she met Sheldon, and would sometimes go to her OB/GYN for some human contact. However, in "The Lunar Excitation" and in "The Robotic Manipulation" Amy states she intentionally only dated once a year. She said this was part of deal with her mother, who in turn did not harass her to date more frequently.
- Raj: Can we please talk about something other than my depressing love life?
- Sheldon: How about Penny’s depressing acting career?
- Leonard: Hey. I mean, it’s been a little tough, but Penny’s following her dreams and in my book that is not depressing.
- Penny: Aw, thank you.
- Bernadette: Raj, your tag’s sticking out.
- Raj: Thank you. That was the closest I’ve come to sex in, like, two years.
- Bernadette: (grunts crossly) Now I feel a little gross.
- Raj: You’re only making it seem more real for me.
- Howard: Hey, that’s my wife. If anyone’s gonna make her feel gross about sex, it’s me.
- Raj: Can we please talk about something other than my depressing love life?
- Sheldon: How about Penny’s depressing acting career?
- Leonard: Hey. I mean, it’s been a little tough, but Penny’s following her dreams, and in my book, that is not depressing.
- Penny: Aw, thank you.
- Howard: Is that book called Lies I Tell to Get Sex?
- Raj: Is that a real book? I would totally read that book.
- Amy: Can I borrow it when you’re done?
- Penny: Well, I’ll have you guys know I turned down a part in a movie last week.
- Leonard: Why would you do that?
- Penny: Because it was crap. It was the sequel to that awful killer gorilla I was in.
- Bernadette: Serial Ape-ist? I thought you died in that!
- Sheldon: She does. Forty-two minutes in.
- Raj: While showering topless, sixteen minutes after a brief side butt during a pillow fight with her sorority sisters.
- Sheldon: I have an eidetic memory. I don’t know what his problem is.
- Penny: Okay. Well there are no shower scenes in this one. They just try to clone me from my corpse, but my DNA gets mixed with the ape’s DNA and I end up running around with giant gorilla hands and feet.
- Sheldon: Am I missing something or isn't that the part she was born to play?
- Leonard: So are you really not gonna do this movie?
- Penny: Well, I don’t think it’s the kind of part that’s good for my career.
- Leonard: Well, but don’t a lot of famous actors get their start doing bad movies?
- Penny: Okay, I don’t think Meryl Streep ever had to say “Must keep gorilla hands from killing again!”
- Raj: If she did, it would be amazing. That woman can do no wrong.
- Leonard: I don’t know anything about show business, so if you think it’s reasonable to turn down paid work and just burn through your savings, I’m sure you know what you’re doing.
- Amy: I think we’re gonna go.
- Sheldon: Are you sure? We were making fun of failed careers. We didn’t get to tap the juicy vein that is Howard’s.
- Howard: Hey, I work at the same university you do.
- Sheldon: Yes, and Hawkeye’s in the Avengers, but no one ever says "Help, Hawkeye".
- Bernadette: (asks Sheldon crossly) Can I ask you something? Why do you constantly feel the need to put down my husband?
- Penny: Oh, I’m sure he does it out of love. The same way my boyfriend makes me feel terrible about my life choices.
- Amy: I think we’re gonna go.
- Leonard: No, no, no. This is not a fight. I was just excited that someone offered you a part and a little surprised that you’d rather sit at home and do nothing than take it. Now it’s a fight.
- Sheldon: Well, with that sorted out, I’m happy to answer your question, Bernadette. Howard started it.
- Howard: I didn’t do anything. I was just sitting here.
- Sheldon: I wasn’t referring to this evening. Ten years ago, upon first seeing me, your husband claimed that I looked like C-3PO and Pee-wee Herman. And he called me C-3P-wee Herman.
- Raj: Ha-a-a. Still funny.
- Bernadette: (she is now very cross) That was ten years ago.
- Sheldon: Nine years, 11 months and three weeks ago, he followed that up by replacing the slides for my lecture with photographs of nude fat women bending over.
- Amy: Really?
- Howard: The lecture was on cosmic gas clouds. That’s funny.
- Raj: I was there. It was funny.
- Sheldon: In any event, that began a decade-long progression of insults, pranks and unwanted magazine subscriptions. To this day, I still get a monthly copy of Granny on Granny. Which, other than its surprisingly fun puzzle page, is complete filth.
- Penny: [Car clanking] Uh, that doesn't sound good.
- Sheldon: Remember the old days when I used to point out that your check engine light was on?
- Penny: Yes.
- Sheldon: Well, get ready to stroll down memory lane. Penny, your check engine....
- Penny: Yeah, I know it’s on, Sheldon! Oh, no, no, no, no. I cannot afford this right now.
- Sheldon: Maybe it’s just something minor. [Engine clanks] [Steam hissing] Ooh, good news, the light just went out.
- Leonard: Are we playing individual or teams?
- Raj: Teams are fun.
- Sheldon: Oh, in that case I’d like to be partnered with my good friend Howard.
- Raj: But I’m always on Howard’s team. We’re best friends. The kind who finish each others…
- Howard: I really don’t think we do tha…
- Raj: Do that. See?
- Penny: Now that girl’s gonna get discovered and become famous and go on Letterman and talk about how she got her big break on some cheap monkey movie all because some dumb girl thought it was beneath her.
- Leonard: At least they talked about you on Letterman.
- (The scene of Bernadette's car)
- Howard: That’s Sheldon. He says he’ll be down in a minute.
- (Howard holds his phone up the ceiling of her car)
- Bernadette: (not very happy by this) What are you doing?
- Howard: Oh, he’s not coming out until he sees proof you don’t have an air freshener in your car.
- Bernadette: (informs him shiftily) This is gonna be a long weekend for you.
- Howard: You’re the reason I’m doing it.
- Bernadette: (snaps at him crossly) I said to stop insulting each other. I didn't tell you to take him on a romantic getaway.
- Howard: How do I know what you said? Damn you and your noise canceling breasts.
- (Bernadette smiles shiftily, just a Sheldon enters the back of Bernadette's car)
- Sheldon: Hello.
- Bernadette: Hi.
- Howard: Hey, buddy.
- Bernadette: You excited for Texas?
- Sheldon: Oh, very much so.
- Howard: It’s not every day you get to tour NASA with a real astronaut.
- Sheldon: Oh, who’s the real astronaut?
- (Bernadette drops her smile for a second and Howard thinks for a few seconds)
- Howard: Buzz Aldrin.
- (Sheldon hits his travel bag with excitement)
- Sheldon: Oh. Yay.
- (Bernadette opens her mouth crossly for a second, Howard looks at Bernadette putting another smile of shiftiness)
- Leonard: Come on, don’t look so sad. You never know what’s gonna happen. Maybe tonight will be great.
- Penny: Sweetie, I know you’re trying to make me feel better, and I love you for that, but it’s making me feel worse, and I kind of hate you.
- (Leonard opens the door to a random car parked by the building)
- Penny: This isn't your car.
- Leonard: I know. (pulls out a key) I thought we’d take yours.
- Penny: I don’t understand.
- Leonard: It’s nothing fancy but it’ll get you to auditions and at least for now you don’t have to go back to waitressing.
- Penny: I don’t know what to say.
- Leonard: Don’t say anything.
- Penny: Oh my God.
- Leonard: I mean you could say thank you, I did just buy you a car.
- Sheldon: [Tap-tap-tap], Howard [Tap-tap-tap], Howard [Tap-tap-tap], Howard.
- Howard: What now?
- Sheldon: I have to go to the bathroom.
- Howard: You just went to the bathroom.
- Sheldon: I didn't use it because it didn't seem safe. Despite all my emails, the toilet didn't have a seat belt.
- Howard: Well, it still doesn't.
- Sheldon: I realize that, but safety concerns went out the window two apple juices ago.
- Howard: How about in the car? I’m an astronaut and you know it. You just don’t like admitting it because you’re jealous.
- Sheldon: Well, truth be told, as a child I did dream of going to space. Those astronauts were my heroes and when you got to go it was hard for me...
- Howard: Thank you.
- Sheldon: ...because it made me realize they'll just send anyone up there.
- Leonard: You sure you want to do this?
- Penny: Yeah. Why wouldn't I want to get my old job back? It’ll be fun to see everyone. I haven’t talk to them since I said, “I quit! See you at the Oscars, bitches.”
- Sheldon: I’m sorry for every mean thing I ever did or said to you.
- Howard: I’m sorry too. It’s all my fault.
- Sheldon: If you weren't my friend, there’d be a hole in my life.
- Howard: Thank you, Sheldon.
- Sheldon: Kind of like when Firefly was canceled. But not as big.
-  Taping Report by Mystery Man